Expressions, functions, and operators in Standard SQL

This page explains BigQuery expressions, including functions and operators.

Function call rules

The following rules apply to all functions unless explicitly indicated otherwise in the function description:

  • For functions that accept numeric types, if one operand is a floating point operand and the other operand is another numeric type, both operands are converted to FLOAT64 before the function is evaluated.
  • If an operand is NULL, the result is NULL, with the exception of the IS operator.
  • For functions that are time zone sensitive (as indicated in the function description), the default time zone, UTC, is used if a time zone is not specified.

SAFE. prefix

Syntax:

SAFE.function_name()

Description

If you begin a function with the SAFE. prefix, it will return NULL instead of an error. The SAFE. prefix only prevents errors from the prefixed function itself: it does not prevent errors that occur while evaluating argument expressions. The SAFE. prefix only prevents errors that occur because of the value of the function inputs, such as "value out of range" errors; other errors, such as internal or system errors, may still occur. If the function does not return an error, SAFE. has no effect on the output. If the function never returns an error, like RAND, then SAFE. has no effect.

Operators, such as + and =, do not support the SAFE. prefix. To prevent errors from a division operation, use SAFE_DIVIDE. Some operators, such as IN, ARRAY, and UNNEST, resemble functions, but do not support the SAFE. prefix. The CAST and EXTRACT functions also do not support the SAFE. prefix. To prevent errors from casting, use SAFE_CAST.

Example

In the following example, the first use of the SUBSTR function would normally return an error, because the function does not support length arguments with negative values. However, the SAFE. prefix causes the function to return NULL instead. The second use of the SUBSTR function provides the expected output: the SAFE. prefix has no effect.

SELECT SAFE.SUBSTR('foo', 0, -2) AS safe_output UNION ALL
SELECT SAFE.SUBSTR('bar', 0, 2) AS safe_output;

+-------------+
| safe_output |
+-------------+
| NULL        |
| ba          |
+-------------+

Supported functions

BigQuery supports the use of the SAFE. prefix with most scalar functions that can raise errors, including STRING functions, math functions, DATE functions, DATETIME functions, and TIMESTAMP functions. BigQuery does not support the use of the SAFE. prefix with aggregate, analytic, or user-defined functions.

Calling persistent user-defined functions (UDFs)

After creating a persistent UDF, you can call it as you would any other function, prepended with the name of the dataset in which it is defined as a prefix.

Syntax

[`project_name`].dataset_name.function_name([parameter_value[, ...]])

To call a UDF in a project other than the project that you are using to run the query, project_name is required.

Examples

The following example creates a UDF named multiply_by_three and calls it from the same project.

CREATE FUNCTION my_dataset.multiply_by_three(x INT64) AS (x * 3);

SELECT my_dataset.multiply_by_three(5) AS result; -- returns 15

The following example calls a persistent UDF from a different project.


CREATE `other_project`.other_dataset.other_function(x INT64, y INT64)
  AS (x * y * 2);

SELECT `other_project`.other_dataset.other_function(3, 4); --returns 24

Conversion rules

"Conversion" includes, but is not limited to, casting and coercion.

  • Casting is explicit conversion and uses the CAST() function.
  • Coercion is implicit conversion, which BigQuery performs automatically under the conditions described below.
  • There is a third group of conversion functions that have their own function names, such as UNIX_DATE().

The table below summarizes all possible CAST and coercion possibilities for BigQuery data types. "Coercion To" applies to all expressions of a given data type, (for example, a column), but literals and parameters can also be coerced. See Literal Coercion and Parameter Coercion for details.

From Type CAST to Coercion To
INT64 BOOL
INT64
NUMERIC
FLOAT64
STRING
NUMERIC
FLOAT64
NUMERIC INT64
NUMERIC
FLOAT64
STRING
FLOAT64
FLOAT64 INT64
NUMERIC
FLOAT64
STRING
 
BOOL BOOL
INT64
STRING
 
STRING BOOL
INT64
NUMERIC
FLOAT64
STRING
BYTES
DATE
DATETIME
TIME
TIMESTAMP
 
BYTES STRING
BYTES
 
DATE STRING
DATE
DATETIME
TIMESTAMP
 
DATETIME STRING
DATE
DATETIME
TIME
TIMESTAMP
 
TIME STRING
TIME
 
TIMESTAMP STRING
DATE
DATETIME
TIME
TIMESTAMP
 
ARRAY ARRAY  
STRUCT STRUCT  

Casting

Syntax:

CAST(expr AS typename)

Cast syntax is used in a query to indicate that the result type of an expression should be converted to some other type.

Example:

CAST(x=1 AS STRING)

This results in "true" if x is 1, "false" for any other non-NULL value, and NULL if x is NULL.

Casts between supported types that do not successfully map from the original value to the target domain produce runtime errors. For example, casting BYTES to STRING where the byte sequence is not valid UTF-8 results in a runtime error.

When casting an expression x of the following types, these rules apply:

From To Rule(s) when casting x
INT64 FLOAT64 Returns a close but potentially not exact FLOAT64 value.
INT64 BOOL Returns FALSE if x is 0, TRUE otherwise.
NUMERIC Floating Point NUMERIC will convert to the closest floating point number with a possible loss of precision.
FLOAT64 INT64 Returns the closest INT64 value.
Halfway cases such as 1.5 or -0.5 round away from zero.
FLOAT64 STRING Returns an approximate string representation.
FLOAT64 NUMERIC The floating point number will round half away from zero. Casting a NaN, +inf or -inf will return an error. Casting a value outside the range of NUMERIC will return an overflow error.
BOOL INT64 Returns 1 if x is TRUE, 0 otherwise.
BOOL STRING Returns "true" if x is TRUE, "false" otherwise.
STRING FLOAT64 Returns x as a FLOAT64 value, interpreting it as having the same form as a valid FLOAT64 literal.
Also supports casts from "inf", "+inf", "-inf", and "nan".
Conversions are case-insensitive.
STRING NUMERIC The numeric literal contained in the STRING must not exceed the maximum precision or range of the NUMERIC type, or an error will occur. If the number of digits after the decimal point exceeds nine, then the resulting NUMERIC value will round half away from zero to have nine digits after the decimal point.
STRING BOOL Returns TRUE if x is "true" and FALSE if x is "false"
All other values of x are invalid and throw an error instead of casting to BOOL.
STRINGs are case-insensitive when converting to BOOL.
STRING BYTES STRINGs are cast to BYTES using UTF-8 encoding. For example, the STRING "©", when cast to BYTES, would become a 2-byte sequence with the hex values C2 and A9.
BYTES STRING Returns x interpreted as a UTF-8 STRING.
For example, the BYTES literal b'\xc2\xa9', when cast to STRING, is interpreted as UTF-8 and becomes the unicode character "©".
An error occurs if x is not valid UTF-8.
ARRAY ARRAY Must be the exact same ARRAY type.
STRUCT STRUCT Allowed if the following conditions are met:
  1. The two STRUCTs have the same number of fields.
  2. The original STRUCT field types can be explicitly cast to the corresponding target STRUCT field types (as defined by field order, not field name).

Safe casting

When using CAST, a query can fail if BigQuery is unable to perform the cast. For example, the following query generates an error:

SELECT CAST("apple" AS INT64) AS not_a_number;

If you want to protect your queries from these types of errors, you can use SAFE_CAST. SAFE_CAST is identical to CAST, except it returns NULL instead of raising an error.

SELECT SAFE_CAST("apple" AS INT64) AS not_a_number;

+--------------+
| not_a_number |
+--------------+
| NULL         |
+--------------+

If you are casting from bytes to strings, you can also use the function, SAFE_CONVERT_BYTES_TO_STRING. Any invalid UTF-8 characters are replaced with the unicode replacement character, U+FFFD. See SAFE_CONVERT_BYTES_TO_STRING for more information.

Casting hex strings to integers

If you are working with hex strings (0x123), you can cast those strings as integers:

SELECT '0x123' as hex_value, CAST('0x123' as INT64) as hex_to_int;

+-----------+------------+
| hex_value | hex_to_int |
+-----------+------------+
| 0x123     | 291        |
+-----------+------------+

SELECT '-0x123' as hex_value, CAST('-0x123' as INT64) as hex_to_int;

+-----------+------------+
| hex_value | hex_to_int |
+-----------+------------+
| -0x123    | -291       |
+-----------+------------+

Casting time types

BigQuery supports casting time types to/from strings as follows:

CAST(time_expression AS STRING)
CAST(string_expression AS TIME)

Casting from a time type to a string is independent of time zone and is of the form HH:MM:SS. When casting from string to time, the string must conform to the supported time literal format, and is independent of time zone. If the string expression is invalid or represents a time that is outside of the supported min/max range, then an error is produced.

Casting date types

BigQuery supports casting date types to/from strings as follows:

CAST(date_expression AS STRING)
CAST(string_expression AS DATE)

Casting from a date type to a string is independent of time zone and is of the form YYYY-MM-DD. When casting from string to date, the string must conform to the supported date literal format, and is independent of time zone. If the string expression is invalid or represents a date that is outside of the supported min/max range, then an error is produced.

Casting datetime types

BigQuery supports casting datetime types to/from strings as follows:

CAST(datetime_expression AS STRING)
CAST(string_expression AS DATETIME)

Casting from a datetime type to a string is independent of time zone and is of the form YYYY-MM-DD HH:MM:SS. When casting from string to datetime, the string must conform to the supported datetime literal format, and is independent of time zone. If the string expression is invalid or represents a datetime that is outside of the supported min/max range, then an error is produced.

Casting timestamp types

BigQuery supports casting timestamp types to/from strings as follows:

CAST(timestamp_expression AS STRING)
CAST(string_expression AS TIMESTAMP)

When casting from timestamp types to string, the timestamp is interpreted using the default time zone, UTC. The number of subsecond digits produced depends on the number of trailing zeroes in the subsecond part: the CAST function will truncate zero, three, or six digits.

When casting from string to a timestamp, string_expression must conform to the supported timestamp literal formats, or else a runtime error occurs. The string_expression may itself contain a time_zone—see time zones. If there is a time zone in the string_expression, that time zone is used for conversion, otherwise the default time zone, UTC, is used. If the string has fewer than six digits, then it is implicitly widened.

An error is produced if the string_expression is invalid, has more than six subsecond digits (i.e. precision greater than microseconds), or represents a time outside of the supported timestamp range.

Casting between date, datetime and timestamp types

BigQuery supports casting between date, datetime and timestamp types as shown in the conversion rules table.

CAST(date_expression AS TIMESTAMP)
CAST(timestamp_expression AS DATE)

Casting from a date to a timestamp interprets date_expression as of midnight (start of the day) in the default time zone, UTC. Casting from a timestamp to date effectively truncates the timestamp as of the default time zone.

CAST(datetime_expression AS TIMESTAMP)
CAST(timestamp_expression AS DATETIME)

Casting from a datetime to a timestamp interprets datetime_expression as of midnight (start of the day) in the default time zone, UTC.

Coercion

BigQuery coerces the result type of an expression to another type if needed to match function signatures. For example, if function func() is defined to take a single argument of type INT64 and an expression is used as an argument that has a result type of FLOAT64, then the result of the expression will be coerced to INT64 type before func() is computed.

Literal coercion

BigQuery supports the following literal coercions:

Input Data Type Result Data Type Notes
STRING literal DATE
DATETIME
TIME
TIMESTAMP

Literal coercion is needed when the actual literal type is different from the type expected by the function in question. For example, if function func() takes a DATE argument, then the expression func("2014-09-27") is valid because the STRING literal "2014-09-27" is coerced to DATE.

Literal conversion is evaluated at analysis time, and gives an error if the input literal cannot be converted successfully to the target type.

Note: String literals do not coerce to numeric types.

Parameter coercion

BigQuery supports the following parameter coercions:

Input Data Type Result Data Type
STRING parameter

If the parameter value cannot be coerced successfully to the target type, an error is provided.

Additional conversion functions

BigQuery provides the following additional conversion functions:

Aggregate functions

An aggregate function is a function that summarizes the rows of a group into a single value. COUNT, MIN and MAX are examples of aggregate functions.

SELECT COUNT(*) as total_count, COUNT(fruit) as non_null_count,
       MIN(fruit) as min, MAX(fruit) as max
FROM (SELECT NULL as fruit UNION ALL
      SELECT "apple" as fruit UNION ALL
      SELECT "pear" as fruit UNION ALL
      SELECT "orange" as fruit)

+-------------+----------------+-------+------+
| total_count | non_null_count | min   | max  |
+-------------+----------------+-------+------+
| 4           | 3              | apple | pear |
+-------------+----------------+-------+------+

When used in conjunction with a GROUP BY clause, the groups summarized typically have at least one row. When the associated SELECT has no GROUP BY clause or when certain aggregate function modifiers filter rows from the group to be summarized it is possible that the aggregate function needs to summarize an empty group. In this case, the COUNT and COUNTIF functions return 0, while all other aggregate functions return NULL.

The following sections describe the aggregate functions that BigQuery supports.

ANY_VALUE

ANY_VALUE(expression)  [OVER (...)]

Description

Returns expression for some row chosen from the group. Which row is chosen is nondeterministic, not random. Returns NULL when the input produces no rows. Returns NULL when expression is NULL for all rows in the group.

ANY_VALUE behaves as if RESPECT NULLS is specified; Rows for which expression is NULL are considered and may be selected.

Supported Argument Types

Any

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Returned Data Types

Matches the input data type.

Examples

SELECT ANY_VALUE(fruit) as any_value
FROM UNNEST(["apple", "banana", "pear"]) as fruit;

+-----------+
| any_value |
+-----------+
| apple     |
+-----------+
SELECT
  fruit,
  ANY_VALUE(fruit) OVER (ORDER BY LENGTH(fruit) ROWS BETWEEN 1 PRECEDING AND CURRENT ROW) AS any_value
FROM UNNEST(["apple", "banana", "pear"]) as fruit;

+--------+-----------+
| fruit  | any_value |
+--------+-----------+
| pear   | pear      |
| apple  | pear      |
| banana | apple     |
+--------+-----------+

ARRAY_AGG

ARRAY_AGG([DISTINCT] expression [{IGNORE|RESPECT} NULLS]
          [ORDER BY key [{ASC|DESC}] [, ... ]]  [LIMIT n])
[OVER (...)]

Description

Returns an ARRAY of expression values.

Supported Argument Types

All data types except ARRAY.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within ARRAY_AGG().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.
  3. IGNORE NULLS or RESPECT NULLS: If IGNORE NULLS is specified, the NULL values are excluded from the result. If RESPECT NULLS is specified or if neither is specified, the NULL values are included in the result. An error is raised if an array in the final query result contains a NULL element.
  4. ORDER BY: Specifies the order of the values.
    • For each sort key, the default sort direction is ASC.
    • NULLs: In the context of the ORDER BY clause, NULLs are the minimum possible value; that is, NULLs appear first in ASC sorts and last in DESC sorts.
    • Floating point data types: see Floating Point Semantics on ordering and grouping.
    • If DISTINCT is also specified, then the sort key must be the same as expression.
    • If ORDER BY is not specified, the order of the elements in the output array is non-deterministic, which means you might receive a different result each time you use this function.
  5. LIMIT: Specifies the maximum number of expression inputs in the result. The limit n must be a constant INT64.

Returned Data Types

ARRAY

If there are zero input rows, this function returns NULL.

Examples

SELECT FORMAT("%T", ARRAY_AGG(x)) AS array_agg
FROM UNNEST([2, 1, -2, 3, -2, 1, 2]) AS x;

+-------------------------+
| array_agg               |
+-------------------------+
| [2, 1, -2, 3, -2, 1, 2] |
+-------------------------+
SELECT FORMAT("%T", ARRAY_AGG(DISTINCT x)) AS array_agg
FROM UNNEST([2, 1, -2, 3, -2, 1, 2]) AS x;

+---------------+
| array_agg     |
+---------------+
| [2, 1, -2, 3] |
+---------------+
SELECT FORMAT("%T", ARRAY_AGG(x IGNORE NULLS)) AS array_agg
FROM UNNEST([NULL, 1, -2, 3, -2, 1, NULL]) AS x;

+-------------------+
| array_agg         |
+-------------------+
| [1, -2, 3, -2, 1] |
+-------------------+
SELECT FORMAT("%T", ARRAY_AGG(x ORDER BY ABS(x))) AS array_agg
FROM UNNEST([2, 1, -2, 3, -2, 1, 2]) AS x;

+-------------------------+
| array_agg               |
+-------------------------+
| [1, 1, 2, -2, -2, 2, 3] |
+-------------------------+
SELECT FORMAT("%T", ARRAY_AGG(x LIMIT 5)) AS array_agg
FROM UNNEST([2, 1, -2, 3, -2, 1, 2]) AS x;

+-------------------+
| array_agg         |
+-------------------+
| [2, 1, -2, 3, -2] |
+-------------------+
SELECT FORMAT("%T", ARRAY_AGG(DISTINCT x IGNORE NULLS ORDER BY x LIMIT 2)) AS array_agg
FROM UNNEST([NULL, 1, -2, 3, -2, 1, NULL]) AS x;

+-----------+
| array_agg |
+-----------+
| [-2, 1]   |
+-----------+
SELECT
  x,
  FORMAT("%T", ARRAY_AGG(x) OVER (ORDER BY ABS(x))) AS array_agg
FROM UNNEST([2, 1, -2, 3, -2, 1, 2]) AS x;

+----+-------------------------+
| x  | array_agg               |
+----+-------------------------+
| 1  | [1, 1]                  |
| 1  | [1, 1]                  |
| 2  | [1, 1, 2, -2, -2, 2]    |
| -2 | [1, 1, 2, -2, -2, 2]    |
| -2 | [1, 1, 2, -2, -2, 2]    |
| 2  | [1, 1, 2, -2, -2, 2]    |
| 3  | [1, 1, 2, -2, -2, 2, 3] |
+----+-------------------------+

ARRAY_CONCAT_AGG

ARRAY_CONCAT_AGG(expression  [ORDER BY key [{ASC|DESC}] [, ... ]]  [LIMIT n])

Description

Concatenates elements from expression of type ARRAY, returning a single ARRAY as a result. This function ignores NULL input arrays, but respects the NULL elements in non-NULL input arrays (an error is raised, however, if an array in the final query result contains a NULL element).

Supported Argument Types

ARRAY

Optional Clauses

The clauses are applied in the following order:

  1. ORDER BY: Specifies the order of the values.
    • For each sort key, the default sort direction is ASC.
    • Array ordering is not supported, and thus the sort key cannot be the same as expression.
    • NULLs: In the context of the ORDER BY clause, NULLs are the minimum possible value; that is, NULLs appear first in ASC sorts and last in DESC sorts.
    • Floating point data types: see Floating Point Semantics on ordering and grouping.
    • If ORDER BY is not specified, the order of the elements in the output array is non-deterministic, which means you might receive a different result each time you use this function.
  2. LIMIT: Specifies the maximum number of expression inputs in the result. The limit applies to the number of input arrays, not the number of elements in the arrays. An empty array counts as 1. A NULL array is not counted. The limit n must be a constant INT64.

Returned Data Types

ARRAY

Returns NULL if there are zero input rows or expression evaluates to NULL for all rows.

Examples

SELECT FORMAT("%T", ARRAY_CONCAT_AGG(x)) AS array_concat_agg FROM (
  SELECT [NULL, 1, 2, 3, 4] AS x
  UNION ALL SELECT NULL
  UNION ALL SELECT [5, 6]
  UNION ALL SELECT [7, 8, 9]
);

+-----------------------------------+
| array_concat_agg                  |
+-----------------------------------+
| [NULL, 1, 2, 3, 4, 5, 6, 7, 8, 9] |
+-----------------------------------+
SELECT FORMAT("%T", ARRAY_CONCAT_AGG(x ORDER BY ARRAY_LENGTH(x))) AS array_concat_agg FROM (
  SELECT [1, 2, 3, 4] AS x
  UNION ALL SELECT [5, 6]
  UNION ALL SELECT [7, 8, 9]
);

+-----------------------------------+
| array_concat_agg                  |
+-----------------------------------+
| [5, 6, 7, 8, 9, 1, 2, 3, 4]       |
+-----------------------------------+
SELECT FORMAT("%T", ARRAY_CONCAT_AGG(x LIMIT 2)) AS array_concat_agg FROM (
  SELECT [1, 2, 3, 4] AS x
  UNION ALL SELECT [5, 6]
  UNION ALL SELECT [7, 8, 9]
);

+--------------------------+
| array_concat_agg         |
+--------------------------+
| [1, 2, 3, 4, 5, 6]       |
+--------------------------+
SELECT FORMAT("%T", ARRAY_CONCAT_AGG(x ORDER BY ARRAY_LENGTH(x) LIMIT 2)) AS array_concat_agg FROM (
  SELECT [1, 2, 3, 4] AS x
  UNION ALL SELECT [5, 6]
  UNION ALL SELECT [7, 8, 9]
);

+------------------+
| array_concat_agg |
+------------------+
| [5, 6, 7, 8, 9]  |
+------------------+

AVG

AVG([DISTINCT] expression)  [OVER (...)]

Description

Returns the average of non-NULL input values, or NaN if the input contains a NaN.

Supported Argument Types

Any numeric input type, such as INT64. Note that, for floating point input types, the return result is non-deterministic, which means you might receive a different result each time you use this function.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within AVG().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Returned Data Types

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

Examples

SELECT AVG(x) as avg
FROM UNNEST([0, 2, 4, 4, 5]) as x;

+-----+
| avg |
+-----+
| 3   |
+-----+
SELECT AVG(DISTINCT x) AS avg
FROM UNNEST([0, 2, 4, 4, 5]) AS x;

+------+
| avg  |
+------+
| 2.75 |
+------+
SELECT
  x,
  AVG(x) OVER (ORDER BY x ROWS BETWEEN 1 PRECEDING AND CURRENT ROW) AS avg
FROM UNNEST([0, 2, NULL, 4, 4, 5]) AS x;

+------+------+
| x    | avg  |
+------+------+
| NULL | NULL |
| 0    | 0    |
| 2    | 1    |
| 4    | 3    |
| 4    | 4    |
| 5    | 4.5  |
+------+------+

BIT_AND

BIT_AND(expression)

Description

Performs a bitwise AND operation on expression and returns the result.

Supported Argument Types

  • INT64

Returned Data Types

INT64

Examples

SELECT BIT_AND(x) as bit_and FROM UNNEST([0xF001, 0x00A1]) as x;

+---------+
| bit_and |
+---------+
| 1       |
+---------+

BIT_OR

BIT_OR(expression)

Description

Performs a bitwise OR operation on expression and returns the result.

Supported Argument Types

  • INT64

Returned Data Types

INT64

Examples

SELECT BIT_OR(x) as bit_or FROM UNNEST([0xF001, 0x00A1]) as x;

+--------+
| bit_or |
+--------+
| 61601  |
+--------+

BIT_XOR

BIT_XOR([DISTINCT] expression)

Description

Performs a bitwise XOR operation on expression and returns the result.

Supported Argument Types

  • INT64

Optional Clause

DISTINCT: Each distinct value of expression is aggregated only once into the result.

Returned Data Types

INT64

Examples

SELECT BIT_XOR(x) AS bit_xor FROM UNNEST([5678, 1234]) AS x;

+---------+
| bit_xor |
+---------+
| 4860    |
+---------+
SELECT BIT_XOR(x) AS bit_xor FROM UNNEST([1234, 5678, 1234]) AS x;

+---------+
| bit_xor |
+---------+
| 5678    |
+---------+
SELECT BIT_XOR(DISTINCT x) AS bit_xor FROM UNNEST([1234, 5678, 1234]) AS x;

+---------+
| bit_xor |
+---------+
| 4860    |
+---------+

COUNT

1. COUNT(*) [OVER (...)]

2. COUNT([DISTINCT] expression) [OVER (...)]

Description

  1. Returns the number of rows in the input.
  2. Returns the number of rows with expression evaluated to any value other than NULL.

Supported Argument Types

expression can be any data type. If DISTINCT is present, expression can only be a data type that is groupable.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions.
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Return Data Types

INT64

Examples

SELECT
  COUNT(*) AS count_star,
  COUNT(DISTINCT x) AS count_dist_x
FROM UNNEST([1, 4, 4, 5]) AS x;

+------------+--------------+
| count_star | count_dist_x |
+------------+--------------+
| 4          | 3            |
+------------+--------------+
SELECT
  x,
  COUNT(*) OVER (PARTITION BY MOD(x, 3)) AS count_star,
  COUNT(DISTINCT x) OVER (PARTITION BY MOD(x, 3)) AS count_dist_x
FROM UNNEST([1, 4, 4, 5]) AS x;

+------+------------+--------------+
| x    | count_star | count_dist_x |
+------+------------+--------------+
| 1    | 3          | 2            |
| 4    | 3          | 2            |
| 4    | 3          | 2            |
| 5    | 1          | 1            |
+------+------------+--------------+
SELECT
  x,
  COUNT(*) OVER (PARTITION BY MOD(x, 3)) AS count_star,
  COUNT(x) OVER (PARTITION BY MOD(x, 3)) AS count_x
FROM UNNEST([1, 4, NULL, 4, 5]) AS x;

+------+------------+---------+
| x    | count_star | count_x |
+------+------------+---------+
| NULL | 1          | 0       |
| 1    | 3          | 3       |
| 4    | 3          | 3       |
| 4    | 3          | 3       |
| 5    | 1          | 1       |
+------+------------+---------+

COUNTIF

COUNTIF(expression)  [OVER (...)]

Description

Returns the count of TRUE values for expression. Returns 0 if there are zero input rows, or if expression evaluates to FALSE or NULL for all rows.

Supported Argument Types

BOOL

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Return Data Types

INT64

Examples

SELECT COUNTIF(x<0) AS num_negative, COUNTIF(x>0) AS num_positive
FROM UNNEST([5, -2, 3, 6, -10, -7, 4, 0]) AS x;

+--------------+--------------+
| num_negative | num_positive |
+--------------+--------------+
| 3            | 4            |
+--------------+--------------+
SELECT
  x,
  COUNTIF(x<0) OVER (ORDER BY ABS(x) ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) AS num_negative
FROM UNNEST([5, -2, 3, 6, -10, NULL, -7, 4, 0]) AS x;

+------+--------------+
| x    | num_negative |
+------+--------------+
| NULL | 0            |
| 0    | 1            |
| -2   | 1            |
| 3    | 1            |
| 4    | 0            |
| 5    | 0            |
| 6    | 1            |
| -7   | 2            |
| -10  | 2            |
+------+--------------+

LOGICAL_AND

LOGICAL_AND(expression)

Description

Returns the logical AND of all non-NULL expressions. Returns NULL if there are zero input rows or expression evaluates to NULL for all rows.

Supported Argument Types

BOOL

Return Data Types

BOOL

Examples

SELECT LOGICAL_AND(x) AS logical_and FROM UNNEST([true, false, true]) AS x;

+-------------+
| logical_and |
+-------------+
| false       |
+-------------+

LOGICAL_OR

LOGICAL_OR(expression)

Description

Returns the logical OR of all non-NULL expressions. Returns NULL if there are zero input rows or expression evaluates to NULL for all rows.

Supported Argument Types

BOOL

Return Data Types

BOOL

Examples

SELECT LOGICAL_OR(x) AS logical_or FROM UNNEST([true, false, true]) AS x;

+------------+
| logical_or |
+------------+
| true       |
+------------+

MAX

MAX(expression)  [OVER (...)]

Description

Returns the maximum value of non-NULL expressions. Returns NULL if there are zero input rows or expression evaluates to NULL for all rows. Returns NaN if the input contains a NaN.

Supported Argument Types

Any data type except: ARRAY STRUCT GEOGRAPHY

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Return Data Types

Same as the data type used as the input values.

Examples

SELECT MAX(x) AS max
FROM UNNEST([8, 37, 4, 55]) AS x;

+-----+
| max |
+-----+
| 55  |
+-----+
SELECT x, MAX(x) OVER (PARTITION BY MOD(x, 2)) AS max
FROM UNNEST([8, NULL, 37, 4, NULL, 55]) AS x;

+------+------+
| x    | max  |
+------+------+
| NULL | NULL |
| NULL | NULL |
| 8    | 8    |
| 4    | 8    |
| 37   | 55   |
| 55   | 55   |
+------+------+

MIN

MIN(expression)  [OVER (...)]

Description

Returns the minimum value of non-NULL expressions. Returns NULL if there are zero input rows or expression evaluates to NULL for all rows. Returns NaN if the input contains a NaN.

Supported Argument Types

Any data type except: ARRAY STRUCT GEOGRAPHY

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Return Data Types

Same as the data type used as the input values.

Examples

SELECT MIN(x) AS min
FROM UNNEST([8, 37, 4, 55]) AS x;

+-----+
| min |
+-----+
| 4   |
+-----+
SELECT x, MIN(x) OVER (PARTITION BY MOD(x, 2)) AS min
FROM UNNEST([8, NULL, 37, 4, NULL, 55]) AS x;

+------+------+
| x    | min  |
+------+------+
| NULL | NULL |
| NULL | NULL |
| 8    | 4    |
| 4    | 4    |
| 37   | 37   |
| 55   | 37   |
+------+------+

STRING_AGG

STRING_AGG([DISTINCT] expression [, delimiter]  [ORDER BY key [{ASC|DESC}] [, ... ]]  [LIMIT n])
[OVER (...)]

Description

Returns a value (either STRING or BYTES) obtained by concatenating non-null values.

If a delimiter is specified, concatenated values are separated by that delimiter; otherwise, a comma is used as a delimiter.

Supported Argument Types

STRING BYTES

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within STRING_AGG().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.
  3. ORDER BY: Specifies the order of the values.
    • For each sort key, the default sort direction is ASC.
    • NULLs: In the context of the ORDER BY clause, NULLs are the minimum possible value; that is, NULLs appear first in ASC sorts and last in DESC sorts.
    • Floating point data types: see Floating Point Semantics on ordering and grouping.
    • If DISTINCT is also specified, then the sort key must be the same as expression.
    • If ORDER BY is not specified, the order of the elements in the output array is non-deterministic, which means you might receive a different result each time you use this function.
  4. LIMIT: Specifies the maximum number of expression inputs in the result. The limit applies to the number of input strings, not the number of characters or bytes in the inputs. An empty string counts as 1. A NULL string is not counted. The limit n must be a constant INT64.

Return Data Types

STRING BYTES

Examples

SELECT STRING_AGG(fruit) AS string_agg
FROM UNNEST(["apple", NULL, "pear", "banana", "pear"]) AS fruit;

+------------------------+
| string_agg             |
+------------------------+
| apple,pear,banana,pear |
+------------------------+
SELECT STRING_AGG(fruit, " & ") AS string_agg
FROM UNNEST(["apple", "pear", "banana", "pear"]) AS fruit;

+------------------------------+
| string_agg                   |
+------------------------------+
| apple & pear & banana & pear |
+------------------------------+
SELECT STRING_AGG(DISTINCT fruit, " & ") AS string_agg
FROM UNNEST(["apple", "pear", "banana", "pear"]) AS fruit;

+-----------------------+
| string_agg            |
+-----------------------+
| apple & pear & banana |
+-----------------------+
SELECT STRING_AGG(fruit, " & " ORDER BY LENGTH(fruit)) AS string_agg
FROM UNNEST(["apple", "pear", "banana", "pear"]) AS fruit;

+------------------------------+
| string_agg                   |
+------------------------------+
| pear & pear & apple & banana |
+------------------------------+
SELECT STRING_AGG(fruit, " & " LIMIT 2) AS string_agg
FROM UNNEST(["apple", "pear", "banana", "pear"]) AS fruit;

+--------------+
| string_agg   |
+--------------+
| apple & pear |
+--------------+
SELECT STRING_AGG(DISTINCT fruit, " & " ORDER BY fruit DESC LIMIT 2) AS string_agg
FROM UNNEST(["apple", "pear", "banana", "pear"]) AS fruit;

+---------------+
| string_agg    |
+---------------+
| pear & banana |
+---------------+
SELECT
  fruit,
  STRING_AGG(fruit, " & ") OVER (ORDER BY LENGTH(fruit)) AS string_agg
FROM UNNEST(["apple", NULL, "pear", "banana", "pear"]) AS fruit;

+--------+------------------------------+
| fruit  | string_agg                   |
+--------+------------------------------+
| NULL   | NULL                         |
| pear   | pear & pear                  |
| pear   | pear & pear                  |
| apple  | pear & pear & apple          |
| banana | pear & pear & apple & banana |
+--------+------------------------------+

SUM

SUM([DISTINCT] expression)  [OVER (...)]

Description

Returns the sum of non-null values.

If the expression is a floating point value, the sum is non-deterministic, which means you might receive a different result each time you use this function.

Supported Argument Types

Any supported numeric data types.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions.
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Return Data Types

INPUTINT64NUMERICFLOAT64
OUTPUTINT64NUMERICFLOAT64

Special cases:

Returns NULL if the input contains only NULLs.

Returns NULL if the input contains no rows.

Returns Inf if the input contains Inf.

Returns -Inf if the input contains -Inf.

Returns NaN if the input contains a NaN.

Returns NaN if the input contains a combination of Inf and -Inf.

Examples

SELECT SUM(x) AS sum
FROM UNNEST([1, 2, 3, 4, 5, 4, 3, 2, 1]) AS x;

+-----+
| sum |
+-----+
| 25  |
+-----+
SELECT SUM(DISTINCT x) AS sum
FROM UNNEST([1, 2, 3, 4, 5, 4, 3, 2, 1]) AS x;

+-----+
| sum |
+-----+
| 15  |
+-----+
SELECT
  x,
  SUM(x) OVER (PARTITION BY MOD(x, 3)) AS sum
FROM UNNEST([1, 2, 3, 4, 5, 4, 3, 2, 1]) AS x;

+---+-----+
| x | sum |
+---+-----+
| 3 | 6   |
| 3 | 6   |
| 1 | 10  |
| 4 | 10  |
| 4 | 10  |
| 1 | 10  |
| 2 | 9   |
| 5 | 9   |
| 2 | 9   |
+---+-----+
SELECT
  x,
  SUM(DISTINCT x) OVER (PARTITION BY MOD(x, 3)) AS sum
FROM UNNEST([1, 2, 3, 4, 5, 4, 3, 2, 1]) AS x;

+---+-----+
| x | sum |
+---+-----+
| 3 | 3   |
| 3 | 3   |
| 1 | 5   |
| 4 | 5   |
| 4 | 5   |
| 1 | 5   |
| 2 | 7   |
| 5 | 7   |
| 2 | 7   |
+---+-----+
SELECT SUM(x) AS sum
FROM UNNEST([]) AS x;

+------+
| sum  |
+------+
| NULL |
+------+

Statistical aggregate functions

BigQuery supports the following statistical aggregate functions.

CORR

CORR(X1, X2)  [OVER (...)]

Description

Returns the Pearson coefficient of correlation of a set of number pairs. For each number pair, the first number is the dependent variable and the second number is the independent variable. The return result is between -1 and 1. A result of 0 indicates no correlation.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any input pairs that contain one or more NULL values. If there are fewer than two input pairs without NULL values, this function returns NULL.

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Return Data Type

FLOAT64

COVAR_POP

COVAR_POP(X1, X2)  [OVER (...)]

Description

Returns the population covariance of a set of number pairs. The first number is the dependent variable; the second number is the independent variable. The return result is between -Inf and +Inf.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any input pairs that contain one or more NULL values. If there is no input pair without NULL values, this function returns NULL. If there is exactly one input pair without NULL values, this function returns 0.

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Return Data Type

FLOAT64

COVAR_SAMP

COVAR_SAMP(X1, X2)  [OVER (...)]

Description

Returns the sample covariance of a set of number pairs. The first number is the dependent variable; the second number is the independent variable. The return result is between -Inf and +Inf.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any input pairs that contain one or more NULL values. If there are fewer than two input pairs without NULL values, this function returns NULL.

Optional Clause

OVER: Specifies a window. See Analytic Functions.

Return Data Type

FLOAT64

STDDEV_POP

STDDEV_POP([DISTINCT] expression)  [OVER (...)]

Description

Returns the population (biased) standard deviation of the values. The return result is between 0 and +Inf.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any NULL inputs. If all inputs are ignored, this function returns NULL.

If this function receives a single non-NULL input, it returns 0.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within STDDEV_POP().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Return Data Type

FLOAT64

STDDEV_SAMP

STDDEV_SAMP([DISTINCT] expression)  [OVER (...)]

Description

Returns the sample (unbiased) standard deviation of the values. The return result is between 0 and +Inf.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any NULL inputs. If there are fewer than two non-NULL inputs, this function returns NULL.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within STDDEV_SAMP().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Return Data Type

FLOAT64

STDDEV

STDDEV([DISTINCT] expression)  [OVER (...)]

Description

An alias of STDDEV_SAMP.

VAR_POP

VAR_POP([DISTINCT] expression)  [OVER (...)]

Description

Returns the population (biased) variance of the values. The return result is between 0 and +Inf.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any NULL inputs. If all inputs are ignored, this function returns NULL.

If this function receives a single non-NULL input, it returns 0.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within VAR_POP().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Return Data Type

FLOAT64

VAR_SAMP

VAR_SAMP([DISTINCT] expression)  [OVER (...)]

Description

Returns the sample (unbiased) variance of the values. The return result is between 0 and +Inf.

All numeric types are supported. If the input is NUMERIC then the internal aggregation is stable with the final output converted to a FLOAT64. Otherwise the input is converted to a FLOAT64 before aggregation, resulting in a potentially unstable result.

This function ignores any NULL inputs. If there are fewer than two non-NULL inputs, this function returns NULL.

Optional Clauses

The clauses are applied in the following order:

  1. OVER: Specifies a window. See Analytic Functions. This clause is currently incompatible with all other clauses within VAR_SAMP().
  2. DISTINCT: Each distinct value of expression is aggregated only once into the result.

Return Data Type

FLOAT64

VARIANCE

VARIANCE([DISTINCT] expression)  [OVER (...)]

Description

An alias of VAR_SAMP.

Approximate aggregate functions

Approximate aggregate functions are scalable in terms of memory usage and time, but produce approximate results instead of exact results. These functions typically require less memory than exact aggregation functions like COUNT(DISTINCT ...), but also introduce statistical uncertainty. This makes approximate aggregation appropriate for large data streams for which linear memory usage is impractical, as well as for data that is already approximate.

The approximate aggregate functions in this section work directly on the input data, rather than an intermediate estimation of the data. These functions do not allow users to specify the precision for the estimation with sketches. If you would like specify precision with sketches, see:

APPROX_COUNT_DISTINCT

APPROX_COUNT_DISTINCT(expression)

Description

Returns the approximate result for COUNT(DISTINCT expression). The value returned is a statistical estimate—not necessarily the actual value.

This function is less accurate than COUNT(DISTINCT expression), but performs better on huge input.

Supported Argument Types

Any data type except: ARRAY STRUCT

Returned Data Types

INT64

Examples

SELECT APPROX_COUNT_DISTINCT(x) as approx_distinct
FROM UNNEST([0, 1, 1, 2, 3, 5]) as x;

+-----------------+
| approx_distinct |
+-----------------+
| 5               |
+-----------------+

APPROX_QUANTILES

APPROX_QUANTILES([DISTINCT] expression, number [{IGNORE|RESPECT} NULLS])

Description

Returns the approximate boundaries for a group of expression values, where number represents the number of quantiles to create. This function returns an array of number + 1 elements, where the first element is the approximate minimum and the last element is the approximate maximum.

Supported Argument Types

expression can be any supported data type except: ARRAY STRUCT

number must be INT64.

Optional Clauses

The clauses are applied in the following order:

  1. DISTINCT: Each distinct value of expression is aggregated only once into the result.
  2. IGNORE NULLS or RESPECT NULLS: If IGNORE NULLS is specified or if neither is specified, the NULL values are excluded from the result. If RESPECT NULLS is specified, the NULL values are included in the result. An error is raised if an array in the final query result contains a NULL element.

Returned Data Types

An ARRAY of the type specified by the expression parameter.

Returns NULL if there are zero input rows or expression evaluates to NULL for all rows.

Examples

SELECT APPROX_QUANTILES(x, 2) AS approx_quantiles
FROM UNNEST([1, 1, 1, 4, 5, 6, 7, 8, 9, 10]) AS x;

+------------------+
| approx_quantiles |
+------------------+
| [1, 5, 10]       |
+------------------+
SELECT APPROX_QUANTILES(x, 100)[OFFSET(90)] AS percentile_90
FROM UNNEST([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) AS x;

+---------------+
| percentile_90 |
+---------------+
| 9             |
+---------------+
SELECT APPROX_QUANTILES(DISTINCT x, 2) AS approx_quantiles
FROM UNNEST([1, 1, 1, 4, 5, 6, 7, 8, 9, 10]) AS x;

+------------------+
| approx_quantiles |
+------------------+
| [1, 6, 10]       |
+------------------+
SELECT FORMAT("%T", APPROX_QUANTILES(x, 2 RESPECT NULLS)) AS approx_quantiles
FROM UNNEST([NULL, NULL, 1, 1, 1, 4, 5, 6, 7, 8, 9, 10]) AS x;

+------------------+
| approx_quantiles |
+------------------+
| [NULL, 4, 10]    |
+------------------+
SELECT FORMAT("%T", APPROX_QUANTILES(DISTINCT x, 2 RESPECT NULLS)) AS approx_quantiles
FROM UNNEST([NULL, NULL, 1, 1, 1, 4, 5, 6, 7, 8, 9, 10]) AS x;

+------------------+
| approx_quantiles |
+------------------+
| [NULL, 6, 10]    |
+------------------+

APPROX_TOP_COUNT

APPROX_TOP_COUNT(expression, number)

Description

Returns the approximate top elements of expression. The number parameter specifies the number of elements returned.

Supported Argument Types

expression can be of any data type that the GROUP BY clause supports.

number must be INT64.

Returned Data Types

An ARRAY of type STRUCT. The STRUCT contains two fields. The first field (named value) contains an input value. The second field (named count) contains an INT64 specifying the number of times the value was returned.

Returns NULL if there are zero input rows.

Examples

SELECT APPROX_TOP_COUNT(x, 2) as approx_top_count
FROM UNNEST(["apple", "apple", "pear", "pear", "pear", "banana"]) as x;

+-------------------------+
| approx_top_count        |
+-------------------------+
| [{pear, 3}, {apple, 2}] |
+-------------------------+

NULL handling

APPROX_TOP_COUNT does not ignore NULLs in the input. For example:

SELECT APPROX_TOP_COUNT(x, 2) as approx_top_count
FROM UNNEST([NULL, "pear", "pear", "pear", "apple", NULL]) as x;

+------------------------+
| approx_top_count       |
+------------------------+
| [{pear, 3}, {NULL, 2}] |
+------------------------+

APPROX_TOP_SUM

APPROX_TOP_SUM(expression, weight, number)

Description

Returns the approximate top elements of expression, based on the sum of an assigned weight. The number parameter specifies the number of elements returned.

If the weight input is negative or NaN, this function returns an error.

Supported Argument Types

expression can be of any data type that the GROUP BY clause supports.

weight must be one of the following:

  • INT64
  • NUMERIC
  • FLOAT64

number must be INT64.

Returned Data Types

An ARRAY of type STRUCT. The STRUCT contains two fields: value and sum. The value field contains the value of the input expression. The sum field is the same type as weight, and is the approximate sum of the input weight associated with the value field.

Returns NULL if there are zero input rows.

Examples

SELECT APPROX_TOP_SUM(x, weight, 2) AS approx_top_sum FROM
UNNEST([
  STRUCT("apple" AS x, 3 AS weight),
  ("pear", 2),
  ("apple", 0),
  ("banana", 5),
  ("pear", 4)
]);

+--------------------------+
| approx_top_sum           |
+--------------------------+
| [{pear, 6}, {banana, 5}] |
+--------------------------+

NULL handling

APPROX_TOP_SUM does not ignore NULL values for the expression and weight parameters.

SELECT APPROX_TOP_SUM(x, weight, 2) AS approx_top_sum FROM
UNNEST([STRUCT("apple" AS x, NULL AS weight), ("pear", 0), ("pear", NULL)]);

+----------------------------+
| approx_top_sum             |
+----------------------------+
| [{pear, 0}, {apple, NULL}] |
+----------------------------+
SELECT APPROX_TOP_SUM(x, weight, 2) AS approx_top_sum FROM
UNNEST([STRUCT("apple" AS x, 0 AS weight), (NULL, 2)]);

+-------------------------+
| approx_top_sum          |
+-------------------------+
| [{NULL, 2}, {apple, 0}] |
+-------------------------+
SELECT APPROX_TOP_SUM(x, weight, 2) AS approx_top_sum FROM
UNNEST([STRUCT("apple" AS x, 0 AS weight), (NULL, NULL)]);

+----------------------------+
| approx_top_sum             |
+----------------------------+
| [{apple, 0}, {NULL, NULL}] |
+----------------------------+

HyperLogLog++ functions

The HyperLogLog++ algorithm (HLL++) estimates cardinality from sketches. If you do not want to work with sketches and do not need customized precision, consider using approximate aggregate functions with system-defined precision.

HLL++ functions are approximate aggregate functions. Approximate aggregation typically requires less memory than exact aggregation functions, like COUNT(DISTINCT), but also introduces statistical uncertainty. This makes HLL++ functions appropriate for large data streams for which linear memory usage is impractical, as well as for data that is already approximate.

BigQuery supports the following HLL++ functions:

HLL_COUNT.INIT

HLL_COUNT.INIT(input [, precision])

Description

An aggregate function that takes one or more input values and aggregates them into a HLL++ sketch. Each sketch is represented using the BYTES data type. You can then merge sketches using HLL_COUNT.MERGE or HLL_COUNT.MERGE_PARTIAL. If no merging is needed, you can extract the final count of distinct values from the sketch using HLL_COUNT.EXTRACT.

This function supports an optional parameter, precision. This parameter defines the accuracy of the estimate at the cost of additional memory required to process the sketches or store them on disk. The following table shows the allowed precision values, the maximum sketch size per group, and confidence interval (CI) of typical precisions:

Precision Max. Sketch Size (KiB) 65% CI 95% CI 99% CI
10 1 ±1.63% ±3.25% ±6.50%
11 2 ±1.15% ±2.30% ±4.60%
12 4 ±0.81% ±1.63% ±3.25%
13 8 ±0.57% ±1.15% ±1.72%
14 16 ±0.41% ±0.81% ±1.22%
15 (default) 32 ±0.29% ±0.57% ±0.86%
16 64 ±0.20% ±0.41% ±0.61%
17 128 ±0.14% ±0.29% ±0.43%
18 256 ±0.10% ±0.20% ±0.41%
19 512 ±0.07% ±0.14% ±0.29%
20 1024 ±0.05% ±0.10% ±0.20%
21 2048 ±0.04% ±0.07% ±0.14%
22 4096 ±0.03% ±0.05% ±0.10%
23 8192 ±0.02% ±0.04% ±0.07%
24 16384 ±0.01% ±0.03% ±0.05%

If the input is NULL, this function returns NULL.

For more information, see HyperLogLog in Practice: Algorithmic Engineering of a State of The Art Cardinality Estimation Algorithm.

Supported input types

INT64, NUMERIC, STRING, BYTES

Return type

BYTES

Example

SELECT
  HLL_COUNT.INIT(respondent) AS respondents_hll,
  flavor,
  country
FROM UNNEST([
  STRUCT(1 AS respondent, "Vanilla" AS flavor, "CH" AS country),
  (1, "Chocolate", "CH"),
  (2, "Chocolate", "US"),
  (2, "Strawberry", "US")])
GROUP BY flavor, country;

HLL_COUNT.MERGE

HLL_COUNT.MERGE(sketch)

Description

An aggregate function that returns the cardinality of several HLL++ set sketches by computing their union.

Each sketch must have the same precision and be initialized on the same type. Attempts to merge sketches with different precisions or for different types results in an error. For example, you cannot merge a sketch initialized from INT64 data with one initialized from STRING data.

This function ignores NULL values when merging sketches. If the merge happens over zero rows or only over NULL values, the function returns 0.

Supported input types

BYTES

Return type

INT64

Example

SELECT HLL_COUNT.MERGE(respondents_hll) AS num_respondents, flavor
FROM (
  SELECT
    HLL_COUNT.INIT(respondent) AS respondents_hll,
    flavor,
    country
  FROM UNNEST([
    STRUCT(1 AS respondent, "Vanilla" AS flavor, "CH" AS country),
    (1, "Chocolate", "CH"),
    (2, "Chocolate", "US"),
    (2, "Strawberry", "US")])
  GROUP BY flavor, country)
GROUP BY flavor;

HLL_COUNT.MERGE_PARTIAL

HLL_COUNT.MERGE_PARTIAL(sketch)

Description

An aggregate function that takes one or more HLL++ sketch inputs and merges them into a new sketch.

This function returns NULL if there is no input or all inputs are NULL.

Supported input types

BYTES

Return type

BYTES

Example

SELECT HLL_COUNT.MERGE_PARTIAL(respondents_hll) AS num_respondents, flavor
FROM (
  SELECT
    HLL_COUNT.INIT(respondent) AS respondents_hll,
    flavor,
    country
  FROM UNNEST([
    STRUCT(1 AS respondent, "Vanilla" AS flavor, "CH" AS country),
    (1, "Chocolate", "CH"),
    (2, "Chocolate", "US"),
    (2, "Strawberry", "US")])
  GROUP BY flavor, country)
GROUP BY flavor;

HLL_COUNT.EXTRACT

HLL_COUNT.EXTRACT(sketch)

Description

A scalar function that extracts a cardinality estimate of a single HLL++ sketch.

If sketch is NULL, this function returns a cardinality estimate of 0.

Supported input types

BYTES

Return type

INT64

Example

SELECT
  flavor,
  country,
  HLL_COUNT.EXTRACT(respondents_hll) AS num_respondents
FROM (
  SELECT
    HLL_COUNT.INIT(respondent) AS respondents_hll,
    flavor,
    country
  FROM UNNEST([
    STRUCT(1 AS respondent, "Vanilla" AS flavor, "CH" AS country),
    (1, "Chocolate", "CH"),
    (2, "Chocolate", "US"),
    (2, "Strawberry", "US")])
  GROUP BY flavor, country);

+------------+---------+-----------------+
| flavor     | country | num_respondents |
+------------+---------+-----------------+
| Vanilla    | CH      | 1               |
| Chocolate  | CH      | 1               |
| Chocolate  | US      | 1               |
| Strawberry | US      | 1               |
+------------+---------+-----------------+

About the HLL++ algorithm

The HLL++ algorithm improves on the HLL algorithm by more accurately estimating very small and large cardinalities. The HLL++ algorithm includes a 64-bit hash function, sparse representation to reduce memory requirements for small cardinality estimates, and empirical bias correction for small cardinality estimates.

About sketches

A sketch is a summary of a large data stream. You can extract statistics from a sketch to estimate particular statistics of the original data, or merge sketches to summarize multiple data streams. A sketch has these features:

  • It compresses raw data into a fixed-memory representation.
  • It's asymptotically smaller than the input.
  • It's the serialized form of an in-memory, sublinear data structure.
  • It typically requires less memory than the input used to create it.

Sketches allow integration with other systems. For example, it is possible to build sketches in external applications, like Cloud Dataflow, or Apache Spark and consume them in BigQuery or vice versa. Sketches also allow building intermediate aggregations for non-additive functions like COUNT(DISTINCT).

Numbering functions

The following sections describe the numbering functions that BigQuery supports. Numbering functions are a subset of analytic functions. For an explanation of how analytic functions work, see Analytic Function Concepts. For a description of how numbering functions work, see the Numbering Function Concepts.

OVER clause requirements:

  • PARTITION BY: Optional.
  • ORDER BY: Required, except for ROW_NUMBER().
  • window_frame_clause: Disallowed.

RANK

Description

Returns the ordinal (1-based) rank of each row within the ordered partition. All peer rows receive the same rank value. The next row or set of peer rows receives a rank value which increments by the number of peers with the previous rank value, instead of DENSE_RANK, which always increments by 1.

Supported Argument Types

INT64

DENSE_RANK

Description

Returns the ordinal (1-based) rank of each row within the window partition. All peer rows receive the same rank value, and the subsequent rank value is incremented by one.

Supported Argument Types

INT64

PERCENT_RANK

Description

Return the percentile rank of a row defined as (RK-1)/(NR-1), where RK is the RANK of the row and NR is the number of rows in the partition. Returns 0 if NR=1.

Supported Argument Types

FLOAT64

CUME_DIST

Description

Return the relative rank of a row defined as NP/NR. NP is defined to be the number of rows that either precede or are peers with the current row. NR is the number of rows in the partition.

Supported Argument Types

FLOAT64

NTILE

NTILE(constant_integer_expression)

Description

This function divides the rows into constant_integer_expression buckets based on row ordering and returns the 1-based bucket number that is assigned to each row. The number of rows in the buckets can differ by at most 1. The remainder values (the remainder of number of rows divided by buckets) are distributed one for each bucket, starting with bucket 1. If constant_integer_expression evaluates to NULL, 0 or negative, an error is provided.

Supported Argument Types

INT64

ROW_NUMBER

Description

Does not require the ORDER BY clause. Returns the sequential row ordinal (1-based) of each row for each ordered partition. If the ORDER BY clause is unspecified then the result is non-deterministic.

Supported Argument Types

INT64

Bit functions

BigQuery supports the following bit functions.

BIT_COUNT

BIT_COUNT(expression)

Description

The input, expression, must be an integer or BYTES.

Returns the number of bits that are set in the input expression. For signed integers, this is the number of bits in two's complement form.

Return Data Type

INT64

Example

SELECT a, BIT_COUNT(a) AS a_bits, FORMAT("%T", b) as b, BIT_COUNT(b) AS b_bits
FROM UNNEST([
  STRUCT(0 AS a, b'' AS b), (0, b'\x00'), (5, b'\x05'), (8, b'\x00\x08'),
  (0xFFFF, b'\xFF\xFF'), (-2, b'\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFE'),
  (-1, b'\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF'),
  (NULL, b'\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF')
]) AS x;

+-------+--------+---------------------------------------------+--------+
| a     | a_bits | b                                           | b_bits |
+-------+--------+---------------------------------------------+--------+
| 0     | 0      | b""                                         | 0      |
| 0     | 0      | b"\x00"                                     | 0      |
| 5     | 2      | b"\x05"                                     | 2      |
| 8     | 1      | b"\x00\x08"                                 | 1      |
| 65535 | 16     | b"\xff\xff"                                 | 16     |
| -2    | 63     | b"\xff\xff\xff\xff\xff\xff\xff\xfe"         | 63     |
| -1    | 64     | b"\xff\xff\xff\xff\xff\xff\xff\xff"         | 64     |
| NULL  | NULL   | b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" | 80     |
+-------+--------+---------------------------------------------+--------+

Mathematical functions

All mathematical functions have the following behaviors:

  • They return NULL if any of the input parameters is NULL.
  • They return NaN if any of the arguments is NaN.

ABS

ABS(X)

Description

Computes absolute value. Returns an error if the argument is an integer and the output value cannot be represented as the same type; this happens only for the largest negative input value, which has no positive representation. Returns +inf for a +/-inf argument.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTINT64NUMERICFLOAT64

SIGN

SIGN(X)

Description

Returns -1, 0, or +1 for negative, zero and positive arguments respectively. For floating point arguments, this function does not distinguish between positive and negative zero. Returns NaN for a NaN argument.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTINT64NUMERICFLOAT64

IS_INF

IS_INF(X)

Description

Returns TRUE if the value is positive or negative infinity.

Returns NULL for NULL inputs.

IS_NAN

IS_NAN(X)

Description

Returns TRUE if the value is a NaN value.

Returns NULL forNULL inputs.

IEEE_DIVIDE

IEEE_DIVIDE(X, Y)

Description

Divides X by Y; this function never fails. Returns FLOAT64. Unlike the division operator (/), this function does not generate errors for division by zero or overflow.

Special cases:

  • If the result overflows, returns +/-inf.
  • If Y=0 and X=0, returns NaN.
  • If Y=0 and X!=0, returns +/-inf.
  • If X = +/-inf and Y = +/-inf, returns NaN.

The behavior of IEEE_DIVIDE is further illustrated in the table below.

Special cases for IEEE_DIVIDE

The following table lists special cases for IEEE_DIVIDE.

Numerator Data Type (X) Denominator Data Type (Y) Result Value
Anything except 0 0 +/-inf
0 0 NaN
0 NaN NaN
NaN 0 NaN
+/-inf +/-inf NaN

RAND

RAND()

Description

Generates a pseudo-random value of type FLOAT64 in the range of [0, 1), inclusive of 0 and exclusive of 1.

SQRT

SQRT(X)

Description

Computes the square root of X. Generates an error if X is less than 0.

Returns +inf if X is +inf.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

POW

POW(X, Y)

Description

Returns the value of X raised to the power of Y. If the result underflows and is not representable, then the function returns a value of zero. Returns an error if one of the following is true:

  • X is a finite value less than 0 and Y is a non-integer
  • X is 0 and Y is a finite value less than 0

Return Data Type The return data type is determined by the argument types with the following table.

INPUTINT64NUMERICFLOAT64
INT64FLOAT64NUMERICFLOAT64
NUMERICNUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

Special cases for POW(X, Y)

The following are special cases for POW(X, Y).

X Y POW(X, Y) or POWER(X, Y)
1.0 Any value including NaN 1.0
any including NaN 0 1.0
-1.0 +/-inf 1.0
ABS(X) < 1 -inf +inf
ABS(X) > 1 -inf 0
ABS(X) < 1 +inf 0
ABS(X) > 1 +inf +inf
-inf Y < 0 0
-inf Y > 0 -inf if Y is an odd integer, +inf otherwise
+inf Y < 0 0
+inf Y > 0 +inf

POWER

POWER(X, Y)

Description

Synonym of POW(X, Y).

EXP

EXP(X)

Description

Computes e to the power of X, also called the natural exponential function. If the result underflows, this function returns a zero. Generates an error if the result overflows. If X is +/-inf, then this function returns +inf or 0.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

LN

LN(X)

Description

Computes the natural logarithm of X. Generates an error if X is less than or equal to zero. If X is +inf, then this function returns +inf.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

LOG

LOG(X [, Y])

Description

If only X is present, LOG is a synonym of LN. If Y is also present, LOG computes the logarithm of X to base Y. Generates an error in these cases:

  • X is less than or equal to zero
  • Y is 1.0
  • Y is less than or equal to zero.

Return Data Type

INPUTINT64NUMERICFLOAT64
INT64FLOAT64NUMERICFLOAT64
NUMERICNUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

The behavior of LOG(X, Y) is further illustrated in the table below.

Special cases for LOG(X, Y)

X Y LOG(X, Y)
-inf Any value NaN
Any value +inf NaN
+inf 0.0 Y < 1.0 -inf
+inf Y > 1.0 +inf

LOG10

LOG10(X)

Description

Similar to LOG, but computes logarithm to base 10.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

GREATEST

GREATEST(X1,...,XN)

Description

Returns NULL if any of the inputs is NULL. Otherwise, returns NaN if any of the inputs is NaN. Otherwise, returns the largest value among X1,...,XN according to the < comparison.

Return Data Types

Data type of the input values.

LEAST

LEAST(X1,...,XN)

Description

Returns NULL if any of the inputs is NULL. Returns NaN if any of the inputs is NaN. Otherwise, returns the smallest value among X1,...,XN according to the > comparison.

Return Data Types

Data type of the input values.

DIV

DIV(X, Y)

Description

Returns the result of integer division of X by Y. Division by zero returns an error. Division by -1 may overflow.

Return Data Type

The return data type is determined by the argument types with the following table.

INPUTINT64NUMERIC
INT64INT64NUMERIC
NUMERICNUMERICNUMERIC

SAFE_DIVIDE

SAFE_DIVIDE(X, Y)

Description

Equivalent to the division operator (X / Y), but returns NULL if an error occurs, such as a division by zero error.

Return Data Type

INPUTINT64NUMERICFLOAT64
INT64FLOAT64NUMERICFLOAT64
NUMERICNUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

SAFE_MULTIPLY

SAFE_MULTIPLY(X, Y)

Description

Equivalent to the multiplication operator (*), but returns NULL if overflow occurs.

Return Data Type

INPUTINT64NUMERICFLOAT64
INT64INT64NUMERICFLOAT64
NUMERICNUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

SAFE_NEGATE

SAFE_NEGATE(X)

Description

Equivalent to the unary minus operator (-), but returns NULL if overflow occurs.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTINT64NUMERICFLOAT64

SAFE_ADD

SAFE_ADD(X, Y)

Description

Equivalent to the addition operator (+), but returns NULL if overflow occurs.

Return Data Type

INPUTINT64NUMERICFLOAT64
INT64INT64NUMERICFLOAT64
NUMERICNUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

SAFE_SUBTRACT

SAFE_SUBTRACT(X, Y)

Description

Returns the result of Y subtracted from X. Equivalent to the subtraction operator (-), but returns NULL if overflow occurs.

Return Data Type

INPUTINT64NUMERICFLOAT64
INT64INT64NUMERICFLOAT64
NUMERICNUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

MOD

MOD(X, Y)

Description

Modulo function: returns the remainder of the division of X by Y. Returned value has the same sign as X. An error is generated if Y is 0.

Return Data Type

The return data type is determined by the argument types with the following table.

INPUTINT64NUMERIC
INT64INT64NUMERIC
NUMERICNUMERICNUMERIC

ROUND

ROUND(X [, N])

Description

If only X is present, ROUND rounds X to the nearest integer. If N is present, ROUND rounds X to N decimal places after the decimal point. If N is negative, ROUND will round off digits to the left of the decimal point. Rounds halfway cases away from zero. Generates an error if overflow occurs.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

TRUNC

TRUNC(X [, N])

Description

If only X is present, TRUNC rounds X to the nearest integer whose absolute value is not greater than the absolute value of X. If N is also present, TRUNC behaves like ROUND(X, N), but always rounds towards zero and never overflows.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

CEIL

CEIL(X)

Description

Returns the smallest integral value that is not less than X.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

CEILING

CEILING(X)

Description

Synonym of CEIL(X)

FLOOR

FLOOR(X)

Description

Returns the largest integral value that is not greater than X.

Return Data Type

INPUTINT64NUMERICFLOAT64
OUTPUTFLOAT64NUMERICFLOAT64

Example rounding function behavior

Example behavior of BigQuery rounding functions:

Input "X" ROUND(X) TRUNC(X) CEIL(X) FLOOR(X)
2.0 2.0 2.0 2.0 2.0
2.3 2.0 2.0 3.0 2.0
2.8 3.0 2.0 3.0 2.0
2.5 3.0 2.0 3.0 2.0
-2.3 -2.0 -2.0 -2.0 -3.0
-2.8 -3.0 -2.0 -2.0 -3.0
-2.5 -3.0 -2.0 -2.0 -3.0
0 0 0 0 0
+/-inf +/-inf +/-inf +/-inf +/-inf
NaN NaN NaN NaN NaN

COS

COS(X)

Description

Computes the cosine of X where X is specified in radians. Never fails.

COSH

COSH(X)

Description

Computes the hyperbolic cosine of X where X is specified in radians. Generates an error if overflow occurs.

ACOS

ACOS(X)

Description

Computes the principal value of the inverse cosine of X. The return value is in the range [0,π]. Generates an error if X is a value outside of the range [-1, 1].

ACOSH

ACOSH(X)

Description

Computes the inverse hyperbolic cosine of X. Generates an error if X is a value less than 1.

SIN

SIN(X)

Description

Computes the sine of X where X is specified in radians. Never fails.

SINH

SINH(X)

Description

Computes the hyperbolic sine of X where X is specified in radians. Generates an error if overflow occurs.

ASIN

ASIN(X)

Description

Computes the principal value of the inverse sine of X. The return value is in the range [-π/2,π/2]. Generates an error if X is outside of the range [-1, 1].

ASINH

ASINH(X)

Description

Computes the inverse hyperbolic sine of X. Does not fail.

TAN

TAN(X)

Description

Computes the tangent of X where X is specified in radians. Generates an error if overflow occurs.

TANH

TANH(X)

Description

Computes the hyperbolic tangent of X where X is specified in radians. Does not fail.

ATAN

ATAN(X)

Description

Computes the principal value of the inverse tangent of X. The return value is in the range [-π/2,π/2]. Does not fail.

ATANH

ATANH(X)

Description

Computes the inverse hyperbolic tangent of X. Generates an error if X is outside of the range [-1, 1].

ATAN2

ATAN2(Y, X)

Description

Calculates the principal value of the inverse tangent of Y/X using the signs of the two arguments to determine the quadrant. The return value is in the range [-π,π].

The behavior of this function is further illustrated in the table below.

Special cases for ATAN2()

Y X ATAN2(Y, X)
NaN Any value NaN
Any value NaN NaN
0 0 0, π or -π depending on the sign of X and Y
Finite value -inf π or -π depending on the sign of Y
Finite value +inf 0
+/-inf Finite value π/2 or π/2 depending on the sign of Y
+/-inf -inf ¾π or -¾π depending on the sign of Y
+/-inf +inf π/4 or -π/4 depending on the sign of Y

Special cases for trigonometric and hyperbolic rounding functions

X COS(X) COSH(X) ACOS(X) ACOSH(X) SIN(X) SINH(X) ASIN(X) ASINH(X) TAN(X) TANH(X) ATAN(X) ATANH(X)
+/-inf NaN =+inf NaN =+inf NaN =+inf NaN =+inf NaN =+1.0 π/2 NaN
-inf NaN =+inf NaN NaN NaN -inf NaN -inf NaN -1.0 -π/2 NaN
NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN

RANGE_BUCKET

RANGE_BUCKET(point, boundaries_array)

Description

RANGE_BUCKET scans through a sorted array and returns the 0-based position of the point's upper bound. This can be useful if you need to group your data to build partitions, histograms, business-defined rules, and more.

RANGE_BUCKET follows these rules:

  • If the point exists in the array, returns the index of the next larger value.

    RANGE_BUCKET(20, [0, 10, 20, 30, 40]) -- 3 is return value
    RANGE_BUCKET(20, [0, 10, 20, 20, 40, 40]) -- 4 is return value
    
  • If the point does not exist in the array, but it falls between two values, returns the index of the larger value.

    RANGE_BUCKET(25, [0, 10, 20, 30, 40]) -- 3 is return value
    
  • If the point is smaller than the first value in the array, returns 0.

    RANGE_BUCKET(-10, [5, 10, 20, 30, 40]) -- 0 is return value
    
  • If the point is greater than or equal to the last value in the array, returns the length of the array.

    RANGE_BUCKET(80, [0, 10, 20, 30, 40]) -- 5 is return value
    
  • If the array is empty, returns 0.

    RANGE_BUCKET(80, []) -- 0 is return value
    
  • If the point is NULL or NaN, returns NULL.

    RANGE_BUCKET(NULL, [0, 10, 20, 30, 40]) -- NULL is return value
    
  • The data type for the point and array must be compatible.

    RANGE_BUCKET('a', ['a', 'b', 'c', 'd']) -- 1 is return value
    RANGE_BUCKET(1.2, [1, 1.2, 1.4, 1.6]) -- 2 is return value
    RANGE_BUCKET(1.2, [1, 2, 4, 6]) -- execution failure
    

Execution failure occurs when:

  • The array has a NaN or NULL value in it.

    RANGE_BUCKET(80, [NULL, 10, 20, 30, 40]) -- execution failure
    
  • The array is not sorted in ascending order.

    RANGE_BUCKET(30, [10, 30, 20, 40, 50]) -- execution failure
    

Parameters

  • point: A generic value.
  • boundaries_array: A generic array of values.

Return Value

INT64

Examples

In a table called students, check to see how many records would exist in each age_group bucket, based on a student's age:

  • age_group 0 (age < 10)
  • age_group 1 (age >= 10, age < 20)
  • age_group 2 (age >= 20, age < 30)
  • age_group 3 (age >= 30)
WITH students AS
(
  SELECT 9 AS age UNION ALL
  SELECT 20 AS age UNION ALL
  SELECT 25 AS age UNION ALL
  SELECT 31 AS age UNION ALL
  SELECT 32 AS age UNION ALL
  SELECT 33 AS age
)
SELECT RANGE_BUCKET(age, [10, 20, 30]) AS age_group, COUNT(*) AS count
FROM students
GROUP BY 1

+--------------+-------+
| age_group    | count |
+--------------+-------+
| 0            | 1     |
| 2            | 2     |
| 3            | 3     |
+--------------+-------+

The following sections describe the navigation functions that BigQuery supports. Navigation functions are a subset of analytic functions. For an explanation of how analytic functions work, see Analytic Function Concepts. For an explanation of how navigation functions work, see Navigation Function Concepts.

FIRST_VALUE

FIRST_VALUE (value_expression [{RESPECT | IGNORE} NULLS])

Description

Returns the value of the value_expression for the first row in the current window frame.

This function includes NULL values in the calculation unless IGNORE NULLS is present. If IGNORE NULLS is present, the function excludes NULL values from the calculation.

Supported Argument Types

value_expression can be any data type that an expression can return.

Return Data Type

Same type as value_expression.

Examples

The following example computes the fastest time for each division.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  FORMAT_TIMESTAMP('%X', finish_time) AS finish_time,
  division,
  FORMAT_TIMESTAMP('%X', fastest_time) AS fastest_time,
  TIMESTAMP_DIFF(finish_time, fastest_time, SECOND) AS delta_in_seconds
FROM (
  SELECT name,
  finish_time,
  division,
  FIRST_VALUE(finish_time)
    OVER (PARTITION BY division ORDER BY finish_time ASC
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS fastest_time
  FROM finishers);

+-----------------+-------------+----------+--------------+------------------+
| name            | finish_time | division | fastest_time | delta_in_seconds |
+-----------------+-------------+----------+--------------+------------------+
| Carly Forte     | 03:08:58    | F25-29   | 03:08:58     | 0                |
| Sophia Liu      | 02:51:45    | F30-34   | 02:51:45     | 0                |
| Nikki Leith     | 02:59:01    | F30-34   | 02:51:45     | 436              |
| Jen Edwards     | 03:06:36    | F30-34   | 02:51:45     | 891              |
| Meghan Lederer  | 03:07:41    | F30-34   | 02:51:45     | 956              |
| Lauren Reasoner | 03:10:14    | F30-34   | 02:51:45     | 1109             |
| Lisa Stelzner   | 02:54:11    | F35-39   | 02:54:11     | 0                |
| Lauren Matthews | 03:01:17    | F35-39   | 02:54:11     | 426              |
| Desiree Berry   | 03:05:42    | F35-39   | 02:54:11     | 691              |
| Suzy Slane      | 03:06:24    | F35-39   | 02:54:11     | 733              |
+-----------------+-------------+----------+--------------+------------------+

LAST_VALUE

LAST_VALUE (value_expression [{RESPECT | IGNORE} NULLS])

Description

Returns the value of the value_expression for the last row in the current window frame.

This function includes NULL values in the calculation unless IGNORE NULLS is present. If IGNORE NULLS is present, the function excludes NULL values from the calculation.

Supported Argument Types

value_expression can be any data type that an expression can return.

Return Data Type

Same type as value_expression.

Examples

The following example computes the slowest time for each division.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  FORMAT_TIMESTAMP('%X', finish_time) AS finish_time,
  division,
  FORMAT_TIMESTAMP('%X', slowest_time) AS slowest_time,
  TIMESTAMP_DIFF(slowest_time, finish_time, SECOND) AS delta_in_seconds
FROM (
  SELECT name,
  finish_time,
  division,
  LAST_VALUE(finish_time)
    OVER (PARTITION BY division ORDER BY finish_time ASC
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS slowest_time
  FROM finishers);

+-----------------+-------------+----------+--------------+------------------+
| name            | finish_time | division | slowest_time | delta_in_seconds |
+-----------------+-------------+----------+--------------+------------------+
| Carly Forte     | 03:08:58    | F25-29   | 03:08:58     | 0                |
| Sophia Liu      | 02:51:45    | F30-34   | 03:10:14     | 1109             |
| Nikki Leith     | 02:59:01    | F30-34   | 03:10:14     | 673              |
| Jen Edwards     | 03:06:36    | F30-34   | 03:10:14     | 218              |
| Meghan Lederer  | 03:07:41    | F30-34   | 03:10:14     | 153              |
| Lauren Reasoner | 03:10:14    | F30-34   | 03:10:14     | 0                |
| Lisa Stelzner   | 02:54:11    | F35-39   | 03:06:24     | 733              |
| Lauren Matthews | 03:01:17    | F35-39   | 03:06:24     | 307              |
| Desiree Berry   | 03:05:42    | F35-39   | 03:06:24     | 42               |
| Suzy Slane      | 03:06:24    | F35-39   | 03:06:24     | 0                |
+-----------------+-------------+----------+--------------+------------------+

NTH_VALUE

NTH_VALUE (value_expression, constant_integer_expression [{RESPECT | IGNORE} NULLS])

Description

Returns the value of value_expression at the Nth row of the current window frame, where Nth is defined by constant_integer_expression. Returns NULL if there is no such row.

This function includes NULL values in the calculation unless IGNORE NULLS is present. If IGNORE NULLS is present, the function excludes NULL values from the calculation.

Supported Argument Types

  • value_expression can be any data type that can be returned from an expression.
  • constant_integer_expression can be any constant expression that returns an integer.

Return Data Type

Same type as value_expression.

Examples

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  FORMAT_TIMESTAMP('%X', finish_time) AS finish_time,
  division,
  FORMAT_TIMESTAMP('%X', fastest_time) AS fastest_time,
  FORMAT_TIMESTAMP('%X', second_fastest) AS second_fastest
FROM (
  SELECT name,
  finish_time,
  division,finishers,
  FIRST_VALUE(finish_time)
    OVER w1 AS fastest_time,
  NTH_VALUE(finish_time, 2)
    OVER w1 as second_fastest
  FROM finishers
  WINDOW w1 AS (
    PARTITION BY division ORDER BY finish_time ASC
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING));

+-----------------+-------------+----------+--------------+----------------+
| name            | finish_time | division | fastest_time | second_fastest |
+-----------------+-------------+----------+--------------+----------------+
| Carly Forte     | 03:08:58    | F25-29   | 03:08:58     | NULL           |
| Sophia Liu      | 02:51:45    | F30-34   | 02:51:45     | 02:59:01       |
| Nikki Leith     | 02:59:01    | F30-34   | 02:51:45     | 02:59:01       |
| Jen Edwards     | 03:06:36    | F30-34   | 02:51:45     | 02:59:01       |
| Meghan Lederer  | 03:07:41    | F30-34   | 02:51:45     | 02:59:01       |
| Lauren Reasoner | 03:10:14    | F30-34   | 02:51:45     | 02:59:01       |
| Lisa Stelzner   | 02:54:11    | F35-39   | 02:54:11     | 03:01:17       |
| Lauren Matthews | 03:01:17    | F35-39   | 02:54:11     | 03:01:17       |
| Desiree Berry   | 03:05:42    | F35-39   | 02:54:11     | 03:01:17       |
| Suzy Slane      | 03:06:24    | F35-39   | 02:54:11     | 03:01:17       |
+-----------------+-------------+----------+--------------+----------------+

LEAD

LEAD (value_expression[, offset [, default_expression]])

Description

Returns the value of the value_expression on a subsequent row. Changing the offset value changes which subsequent row is returned; the default value is 1, indicating the next row in the window frame. An error occurs if offset is NULL or a negative value.

The optional default_expression is used if there isn't a row in the window frame at the specified offset. This expression must be a constant expression and its type must be implicitly coercible to the type of value_expression. If left unspecified, default_expression defaults to NULL.

Supported Argument Types

  • value_expression can be any data type that can be returned from an expression.
  • offset must be a non-negative integer literal or parameter.
  • default_expression must be compatible with the value expression type.

Return Data Type

Same type as value_expression.

Examples

The following example illustrates a basic use of the LEAD function.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LEAD(name)
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS followed_by
FROM finishers;

+-----------------+-------------+----------+-----------------+
| name            | finish_time | division | followed_by     |
+-----------------+-------------+----------+-----------------+
| Carly Forte     | 03:08:58    | F25-29   | NULL            |
| Sophia Liu      | 02:51:45    | F30-34   | Nikki Leith     |
| Nikki Leith     | 02:59:01    | F30-34   | Jen Edwards     |
| Jen Edwards     | 03:06:36    | F30-34   | Meghan Lederer  |
| Meghan Lederer  | 03:07:41    | F30-34   | Lauren Reasoner |
| Lauren Reasoner | 03:10:14    | F30-34   | NULL            |
| Lisa Stelzner   | 02:54:11    | F35-39   | Lauren Matthews |
| Lauren Matthews | 03:01:17    | F35-39   | Desiree Berry   |
| Desiree Berry   | 03:05:42    | F35-39   | Suzy Slane      |
| Suzy Slane      | 03:06:24    | F35-39   | NULL            |
+-----------------+-------------+----------+-----------------+

This next example uses the optional offset parameter.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LEAD(name, 2)
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_back
FROM finishers;

+-----------------+-------------+----------+------------------+
| name            | finish_time | division | two_runners_back |
+-----------------+-------------+----------+------------------+
| Carly Forte     | 03:08:58    | F25-29   | NULL             |
| Sophia Liu      | 02:51:45    | F30-34   | Jen Edwards      |
| Nikki Leith     | 02:59:01    | F30-34   | Meghan Lederer   |
| Jen Edwards     | 03:06:36    | F30-34   | Lauren Reasoner  |
| Meghan Lederer  | 03:07:41    | F30-34   | NULL             |
| Lauren Reasoner | 03:10:14    | F30-34   | NULL             |
| Lisa Stelzner   | 02:54:11    | F35-39   | Desiree Berry    |
| Lauren Matthews | 03:01:17    | F35-39   | Suzy Slane       |
| Desiree Berry   | 03:05:42    | F35-39   | NULL             |
| Suzy Slane      | 03:06:24    | F35-39   | NULL             |
+-----------------+-------------+----------+------------------+

The following example replaces NULL values with a default value.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LEAD(name, 2, 'Nobody')
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_back
FROM finishers;

+-----------------+-------------+----------+------------------+
| name            | finish_time | division | two_runners_back |
+-----------------+-------------+----------+------------------+
| Carly Forte     | 03:08:58    | F25-29   | Nobody           |
| Sophia Liu      | 02:51:45    | F30-34   | Jen Edwards      |
| Nikki Leith     | 02:59:01    | F30-34   | Meghan Lederer   |
| Jen Edwards     | 03:06:36    | F30-34   | Lauren Reasoner  |
| Meghan Lederer  | 03:07:41    | F30-34   | Nobody           |
| Lauren Reasoner | 03:10:14    | F30-34   | Nobody           |
| Lisa Stelzner   | 02:54:11    | F35-39   | Desiree Berry    |
| Lauren Matthews | 03:01:17    | F35-39   | Suzy Slane       |
| Desiree Berry   | 03:05:42    | F35-39   | Nobody           |
| Suzy Slane      | 03:06:24    | F35-39   | Nobody           |
+-----------------+-------------+----------+------------------+

LAG

LAG (value_expression[, offset [, default_expression]])

Description

Returns the value of the value_expression on a preceding row. Changing the offset value changes which preceding row is returned; the default value is 1, indicating the previous row in the window frame. An error occurs if offset is NULL or a negative value.

The optional default_expression is used if there isn't a row in the window frame at the specified offset. This expression must be a constant expression and its type must be implicitly coercible to the type of value_expression. If left unspecified, default_expression defaults to NULL.

Supported Argument Types

  • value_expression can be any data type that can be returned from an expression.
  • offset must be a non-negative integer literal or parameter.
  • default_expression must be compatible with the value expression type.

Return Data Type

Same type as value_expression.

Examples

The following example illustrates a basic use of the LAG function.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LAG(name)
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS preceding_runner
FROM finishers;

+-----------------+-------------+----------+------------------+
| name            | finish_time | division | preceding_runner |
+-----------------+-------------+----------+------------------+
| Carly Forte     | 03:08:58    | F25-29   | NULL             |
| Sophia Liu      | 02:51:45    | F30-34   | NULL             |
| Nikki Leith     | 02:59:01    | F30-34   | Sophia Liu       |
| Jen Edwards     | 03:06:36    | F30-34   | Nikki Leith      |
| Meghan Lederer  | 03:07:41    | F30-34   | Jen Edwards      |
| Lauren Reasoner | 03:10:14    | F30-34   | Meghan Lederer   |
| Lisa Stelzner   | 02:54:11    | F35-39   | NULL             |
| Lauren Matthews | 03:01:17    | F35-39   | Lisa Stelzner    |
| Desiree Berry   | 03:05:42    | F35-39   | Lauren Matthews  |
| Suzy Slane      | 03:06:24    | F35-39   | Desiree Berry    |
+-----------------+-------------+----------+------------------+

This next example uses the optional offset parameter.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LAG(name, 2)
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_ahead
FROM finishers;

+-----------------+-------------+----------+-------------------+
| name            | finish_time | division | two_runners_ahead |
+-----------------+-------------+----------+-------------------+
| Carly Forte     | 03:08:58    | F25-29   | NULL              |
| Sophia Liu      | 02:51:45    | F30-34   | NULL              |
| Nikki Leith     | 02:59:01    | F30-34   | NULL              |
| Jen Edwards     | 03:06:36    | F30-34   | Sophia Liu        |
| Meghan Lederer  | 03:07:41    | F30-34   | Nikki Leith       |
| Lauren Reasoner | 03:10:14    | F30-34   | Jen Edwards       |
| Lisa Stelzner   | 02:54:11    | F35-39   | NULL              |
| Lauren Matthews | 03:01:17    | F35-39   | NULL              |
| Desiree Berry   | 03:05:42    | F35-39   | Lisa Stelzner     |
| Suzy Slane      | 03:06:24    | F35-39   | Lauren Matthews   |
+-----------------+-------------+----------+-------------------+

The following example replaces NULL values with a default value.

WITH finishers AS
 (SELECT 'Sophia Liu' as name,
  TIMESTAMP '2016-10-18 2:51:45' as finish_time,
  'F30-34' as division
  UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
  UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
  UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
  UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
  UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
  UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
  UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
  UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
  UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
  finish_time,
  division,
  LAG(name, 2, 'Nobody')
    OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_ahead
FROM finishers;

+-----------------+-------------+----------+-------------------+
| name            | finish_time | division | two_runners_ahead |
+-----------------+-------------+----------+-------------------+
| Carly Forte     | 03:08:58    | F25-29   | Nobody            |
| Sophia Liu      | 02:51:45    | F30-34   | Nobody            |
| Nikki Leith     | 02:59:01    | F30-34   | Nobody            |
| Jen Edwards     | 03:06:36    | F30-34   | Sophia Liu        |
| Meghan Lederer  | 03:07:41    | F30-34   | Nikki Leith       |
| Lauren Reasoner | 03:10:14    | F30-34   | Jen Edwards       |
| Lisa Stelzner   | 02:54:11    | F35-39   | Nobody            |
| Lauren Matthews | 03:01:17    | F35-39   | Nobody            |
| Desiree Berry   | 03:05:42    | F35-39   | Lisa Stelzner     |
| Suzy Slane      | 03:06:24    | F35-39   | Lauren Matthews   |
+-----------------+-------------+----------+-------------------+

PERCENTILE_CONT

PERCENTILE_CONT (value_expression, percentile [{RESPECT | IGNORE} NULLS])

Description

Computes the specified percentile value for the value_expression, with linear interpolation.

This function ignores NULL values if RESPECT NULLS is absent. If RESPECT NULLS is present:

  • Interpolation between two NULL values returns NULL.
  • Interpolation between a NULL value and a non-NULL value returns the non-NULL value.

Supported Argument Types

  • value_expression and percentile must have one of the following types:

    • NUMERIC

    • FLOAT64

  • percentile must be a literal in the range [0, 1].

Return Data Type

The return data type is determined by the argument types with the following table.

INPUTNUMERICFLOAT64
NUMERICNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64

Examples

The following example computes the value for some percentiles from a column of values while ignoring nulls.

SELECT
  PERCENTILE_CONT(x, 0) OVER() AS min,
  PERCENTILE_CONT(x, 0.01) OVER() AS percentile1,
  PERCENTILE_CONT(x, 0.5) OVER() AS median,
  PERCENTILE_CONT(x, 0.9) OVER() AS percentile90,
  PERCENTILE_CONT(x, 1) OVER() AS max
FROM UNNEST([0, 3, NULL, 1, 2]) AS x LIMIT 1;

+-----+-------------+--------+--------------+-----+
| min | percentile1 | median | percentile90 | max |
+-----+-------------+--------+--------------+-----+
| 0   | 0.03        | 1.5    | 2.7          | 3   |
+-----+-------------+--------+--------------+-----+

The following example computes the value for some percentiles from a column of values while respecting nulls.

SELECT
  PERCENTILE_CONT(x, 0 RESPECT NULLS) OVER() AS min,
  PERCENTILE_CONT(x, 0.01 RESPECT NULLS) OVER() AS percentile1,
  PERCENTILE_CONT(x, 0.5 RESPECT NULLS) OVER() AS median,
  PERCENTILE_CONT(x, 0.9 RESPECT NULLS) OVER() AS percentile90,
  PERCENTILE_CONT(x, 1 RESPECT NULLS) OVER() AS max
FROM UNNEST([0, 3, NULL, 1, 2]) AS x LIMIT 1;

+------+-------------+--------+--------------+-----+
| min  | percentile1 | median | percentile90 | max |
+------+-------------+--------+--------------+-----+
| NULL | 0           | 1      | 2.6          | 3   |
+------+-------------+--------+--------------+-----+

PERCENTILE_DISC

PERCENTILE_DISC (value_expression, percentile [{RESPECT | IGNORE} NULLS])

Description

Computes the specified percentile value for a discrete value_expression. The returned value is the first sorted value of value_expression with cumulative distribution greater than or equal to the given percentile value.

This function ignores NULL values unless RESPECT NULLS is present.

Supported Argument Types

  • value_expression can be any orderable type.
  • percentile must be a literal in the range [0, 1], with one of the following types:

    • NUMERIC

    • FLOAT64

Return Data Type

Same type as value_expression.

Examples

The following example computes the value for some percentiles from a column of values while ignoring nulls.

SELECT
  x,
  PERCENTILE_DISC(x, 0) OVER() AS min,
  PERCENTILE_DISC(x, 0.5) OVER() AS median,
  PERCENTILE_DISC(x, 1) OVER() AS max
FROM UNNEST(['c', NULL, 'b', 'a']) AS x;

+------+-----+--------+-----+
| x    | min | median | max |
+------+-----+--------+-----+
| c    | a   | b      | c   |
| NULL | a   | b      | c   |
| b    | a   | b      | c   |
| a    | a   | b      | c   |
+------+-----+--------+-----+

The following example computes the value for some percentiles from a column of values while respecting nulls.

SELECT
  x,
  PERCENTILE_DISC(x, 0 RESPECT NULLS) OVER() AS min,
  PERCENTILE_DISC(x, 0.5 RESPECT NULLS) OVER() AS median,
  PERCENTILE_DISC(x, 1 RESPECT NULLS) OVER() AS max
FROM UNNEST(['c', NULL, 'b', 'a']) AS x;

+------+------+--------+-----+
| x    | min  | median | max |
+------+------+--------+-----+
| c    | NULL | a      | c   |
| NULL | NULL | a      | c   |
| b    | NULL | a      | c   |
| a    | NULL | a      | c   |
+------+------+--------+-----+

Aggregate analytic functions

The following sections describe the aggregate analytic functions that BigQuery supports. For an explanation of how analytic functions work, see Analytic Function Concepts. For an explanation of how aggregate analytic functions work, see Aggregate Analytic Function Concepts.

BigQuery supports the following aggregate functions as analytic functions:

OVER clause requirements:

  • PARTITION BY: Optional.
  • ORDER BY: Optional. Disallowed if DISTINCT is present.
  • window_frame_clause: Optional. Disallowed if DISTINCT is present.

Example:

COUNT(*) OVER (ROWS UNBOUNDED PRECEDING)
SUM(DISTINCT x) OVER ()

Hash functions

FARM_FINGERPRINT

FARM_FINGERPRINT(value)

Description

Computes the fingerprint of the STRING or BYTES input using the Fingerprint64 function from the open-source FarmHash library. The output of this function for a particular input will never change.

Return type

INT64

Examples

WITH example AS (
  SELECT 1 AS x, "foo" AS y, true AS z UNION ALL
  SELECT 2 AS x, "apple" AS y, false AS z UNION ALL
  SELECT 3 AS x, "" AS y, true AS z
)
SELECT
  *,
  FARM_FINGERPRINT(CONCAT(CAST(x AS STRING), y, CAST(z AS STRING)))
    AS row_fingerprint
FROM example;
+---+-------+-------+----------------------+
| x | y     | z     | row_fingerprint      |
+---+-------+-------+----------------------+
| 1 | foo   | true  | -1541654101129638711 |
| 2 | apple | false | 2794438866806483259  |
| 3 |       | true  | -4880158226897771312 |
+---+-------+-------+----------------------+

MD5

MD5(input)

Description

Computes the hash of the input using the MD5 algorithm. The input can either be STRING or BYTES. The string version treats the input as an array of bytes.

This function returns 16 bytes.

Return type

BYTES

Example

SELECT MD5("Hello World") as md5;

-- Note that the result of MD5 is of type BYTES, displayed as a base64-encoded string.
+--------------------------+
| md5                      |
+--------------------------+
| sQqNsWTgdUEFt6mb5y4/5Q== |
+--------------------------+

SHA1

SHA1(input)

Description

Computes the hash of the input using the SHA-1 algorithm. The input can either be STRING or BYTES. The string version treats the input as an array of bytes.

This function returns 20 bytes.

Return type

BYTES

Example

SELECT SHA1("Hello World") as sha1;

-- Note that the result of SHA1 is of type BYTES, displayed as a base64-encoded string.
+------------------------------+
| sha1                         |
+------------------------------+
| Ck1VqNd45QIvq3AZd8XYQLvEhtA= |
+------------------------------+

SHA256

SHA256(input)

Description

Computes the hash of the input using the SHA-256 algorithm. The input can either be STRING or BYTES. The string version treats the input as an array of bytes.

This function returns 32 bytes.

Return type

BYTES

Example

SELECT SHA256("Hello World") as sha256;

SHA512

SHA512(input)

Description

Computes the hash of the input using the SHA-512 algorithm. The input can either be STRING or BYTES. The string version treats the input as an array of bytes.

This function returns 64 bytes.

Return type

BYTES

Example

SELECT SHA512("Hello World") as sha512;

String functions

These string functions work on two different values: STRING and BYTES data types. STRING values must be well-formed UTF-8.

Functions that return position values, such as STRPOS, encode those positions as INT64. The value 1 refers to the first character (or byte), 2 refers to the second, and so on. The value 0 indicates an invalid index. When working on STRING types, the returned positions refer to character positions.

All string comparisons are done byte-by-byte, without regard to Unicode canonical equivalence.

ASCII

ASCII(value)

Description

Returns the ASCII code for the first character or byte in value. Returns 0 if value is empty or the ASCII code is 0 for the first character or byte.

Return type

INT64

Examples

SELECT ASCII('abcd') as A, ASCII('a') as B, ASCII('') as C, ASCII(NULL) as D;

+-------+-------+-------+-------+
| A     | B     | C     | D     |
+-------+-------+-------+-------+
| 97    | 97    | 0     | NULL  |
+-------+-------+-------+-------+

BYTE_LENGTH

BYTE_LENGTH(value)

Description

Returns the length of the STRING or BYTES value in BYTES, regardless of whether the type of the value is STRING or BYTES.

Return type

INT64

Examples

WITH example AS
  (SELECT "абвгд" AS characters, b"абвгд" AS bytes)

SELECT
  characters,
  BYTE_LENGTH(characters) AS string_example,
  bytes,
  BYTE_LENGTH(bytes) AS bytes_example
FROM example;

+------------+----------------+-------+---------------+
| characters | string_example | bytes | bytes_example |
+------------+----------------+-------+---------------+
| абвгд      | 10             | абвгд | 10            |
+------------+----------------+-------+---------------+

CHAR_LENGTH

CHAR_LENGTH(value)

Description

Returns the length of the STRING in characters.

Return type

INT64

Examples

WITH example AS
  (SELECT "абвгд" AS characters)

SELECT
  characters,
  CHAR_LENGTH(characters) AS char_length_example
FROM example;

+------------+---------------------+
| characters | char_length_example |
+------------+---------------------+
| абвгд      |                   5 |
+------------+---------------------+

CHARACTER_LENGTH

CHARACTER_LENGTH(value)

Description

Synonym for CHAR_LENGTH.

Return type

INT64

Examples

WITH example AS
  (SELECT "абвгд" AS characters)

SELECT
  characters,
  CHARACTER_LENGTH(characters) AS char_length_example
FROM example;

+------------+---------------------+
| characters | char_length_example |
+------------+---------------------+
| абвгд      |                   5 |
+------------+---------------------+

CHR

CHR(value)

Description

Takes a Unicode code point and returns the character that matches the code point. Each valid code point should fall within the range of [0, 0xD7FF] and [0xE000, 0x10FFFF]. Returns an empty string if the code point is 0. If an invalid Unicode code point is specified, an error is returned.

To work with an array of Unicode code points, see CODE_POINTS_TO_STRING

Return type

STRING

Examples

SELECT CHR(65) AS A, CHR(255) AS B, CHR(513) AS C, CHR(1024)  AS D;

+-------+-------+-------+-------+
| A     | B     | C     | D     |
+-------+-------+-------+-------+
| A     | ÿ     | ȁ     | Ѐ     |
+-------+-------+-------+-------+
SELECT CHR(97) AS A, CHR(0xF9B5) AS B, CHR(0) AS C, CHR(NULL) AS D;

+-------+-------+-------+-------+
| A     | B     | C     | D     |
+-------+-------+-------+-------+
| a     | 例    |       | NULL  |
+-------+-------+-------+-------+

CODE_POINTS_TO_BYTES

CODE_POINTS_TO_BYTES(ascii_values)

Description

Takes an array of extended ASCII code points (ARRAY of INT64) and returns BYTES.

To convert from BYTES to an array of code points, see TO_CODE_POINTS.

Return type

BYTES

Examples

The following is a basic example using CODE_POINTS_TO_BYTES.

SELECT CODE_POINTS_TO_BYTES([65, 98, 67, 100]) AS bytes;

-- Note that the result of CODE_POINTS_TO_BYTES is of type BYTES, displayed as a base64-encoded string.
-- In BYTES format, b'AbCd' is the result.
+----------+
| bytes    |
+----------+
| QWJDZA== |
+----------+

The following example uses a rotate-by-13 places (ROT13) algorithm to encode a string.

SELECT CODE_POINTS_TO_BYTES(ARRAY_AGG(
  (SELECT
      CASE
        WHEN chr BETWEEN b'a' and b'z'
          THEN TO_CODE_POINTS(b'a')[offset(0)] +
            MOD(code+13-TO_CODE_POINTS(b'a')[offset(0)],26)
        WHEN chr BETWEEN b'A' and b'Z'
          THEN TO_CODE_POINTS(b'A')[offset(0)] +
            MOD(code+13-TO_CODE_POINTS(b'A')[offset(0)],26)
        ELSE code
      END
   FROM
     (SELECT code, CODE_POINTS_TO_BYTES([code]) chr)
  ) ORDER BY OFFSET)) AS encoded_string
FROM UNNEST(TO_CODE_POINTS(b'Test String!')) code WITH OFFSET;

-- Note that the result of CODE_POINTS_TO_BYTES is of type BYTES, displayed as a base64-encoded string.
-- In BYTES format, b'Grfg Fgevat!' is the result.
+------------------+
| encoded_string   |
+------------------+
| R3JmZyBGZ2V2YXQh |
+------------------+

CODE_POINTS_TO_STRING

CODE_POINTS_TO_STRING(value)

Description

Takes an array of Unicode code points (ARRAY of INT64) and returns a STRING. If a code point is 0, does not return a character for it in the STRING.

To convert from a string to an array of code points, see TO_CODE_POINTS.

Return type

STRING

Examples

The following are basic examples using CODE_POINTS_TO_STRING.

SELECT CODE_POINTS_TO_STRING([65, 255, 513, 1024]) AS string;

+--------+
| string |
+--------+
| AÿȁЀ   |
+--------+
SELECT CODE_POINTS_TO_STRING([97, 0, 0xF9B5]) AS string;

+--------+
| string |
+--------+
| a例    |
+--------+
SELECT CODE_POINTS_TO_STRING([65, 255, NULL, 1024]) AS string;

+--------+
| string |
+--------+
| NULL   |
+--------+

The following example computes the frequency of letters in a set of words.

WITH Words AS (
  SELECT word
  FROM UNNEST(['foo', 'bar', 'baz', 'giraffe', 'llama']) AS word
)
SELECT
  CODE_POINTS_TO_STRING([code_point]) AS letter,
  COUNT(*) AS letter_count
FROM Words,
  UNNEST(TO_CODE_POINTS(word)) AS code_point
GROUP BY 1
ORDER BY 2 DESC;

+--------+--------------+
| letter | letter_count |
+--------+--------------+
| a      | 5            |
| f      | 3            |
| r      | 2            |
| b      | 2            |
| l      | 2            |
| o      | 2            |
| g      | 1            |
| z      | 1            |
| e      | 1            |
| m      | 1            |
| i      | 1            |
+--------+--------------+

CONCAT

CONCAT(value1[, ...])

Description

Concatenates one or more values into a single result. All values must be BYTES or data types that can be cast to STRING.

The function returns NULL if any input argument is NULL.

Return type

STRING or BYTES

Examples

SELECT CONCAT("T.P.", " ", "Bar") as author;

+---------------------+
| author              |
+---------------------+
| T.P. Bar            |
+---------------------+
SELECT CONCAT("Summer", " ", 1923) as release_date;

+---------------------+
| release_date        |
+---------------------+
| Summer 1923         |
+---------------------+

With Employees AS
  (SELECT
    "John" AS first_name,
    "Doe" AS last_name
  UNION ALL
  SELECT
    "Jane" AS first_name,
    "Smith" AS last_name
  UNION ALL
  SELECT
    "Joe" AS first_name,
    "Jackson" AS last_name)

SELECT
  CONCAT(first_name, " ", last_name)
  AS full_name
FROM Employees;

+---------------------+
| full_name           |
+---------------------+
| John Doe            |
| Jane Smith          |
| Joe Jackson         |
+---------------------+

ENDS_WITH

ENDS_WITH(value1, value2)

Description

Takes two STRING or BYTES values. Returns TRUE if the second value is a suffix of the first.

Return type

BOOL

Examples

WITH items AS
  (SELECT "apple" as item
  UNION ALL
  SELECT "banana" as item
  UNION ALL
  SELECT "orange" as item)

SELECT
  ENDS_WITH(item, "e") as example
FROM items;

+---------+
| example |
+---------+
|    True |
|   False |
|    True |
+---------+

FORMAT

BigQuery supports a FORMAT() function for formatting strings. This function is similar to the C printf function. It produces a STRING from a format string that contains zero or more format specifiers, along with a variable length list of additional arguments that matches the format specifiers. Here are some examples:

Description Statement Result
Simple integer FORMAT("%d", 10) 10
Integer with left blank padding FORMAT("|%10d|", 11) |           11|
Integer with left zero padding FORMAT("+%010d+", 12) +0000000012+
Integer with commas FORMAT("%'d", 123456789) 123,456,789
STRING FORMAT("-%s-", 'abcd efg') -abcd efg-
FLOAT64 FORMAT("%f %E", 1.1, 2.2) 1.100000 2.200000E+00
DATE FORMAT("%t", date "2015-09-01") 2015-09-01
TIMESTAMP FORMAT("%t", timestamp "2015-09-01 12:34:56 America/Los_Angeles") 2015‑09‑01 19:34:56+00

The FORMAT() function does not provide fully customizable formatting for all types and values, nor formatting that is sensitive to locale.

If custom formatting is necessary for a type, you must first format it using type-specific format functions, such as FORMAT_DATE() or FORMAT_TIMESTAMP(). For example:

SELECT FORMAT("date: %s!", FORMAT_DATE("%B %d, %Y", date '2015-01-02'));

Returns

date: January 02, 2015!

Syntax

The FORMAT() syntax takes a format string and variable length list of arguments and produces a STRING result:

FORMAT(format_string, ...)

The format_string expression can contain zero or more format specifiers. Each format specifier is introduced by the % symbol, and must map to one or more of the remaining arguments. For the most part, this is a one-to-one mapping, except when the * specifier is present. For example, %.*i maps to two arguments—a length argument and a signed integer argument. If the number of arguments related to the format specifiers is not the same as the number of arguments, an error occurs.

Supported format specifiers

The FORMAT() function format specifier follows this prototype:

%[flags][width][.precision]specifier

The supported format specifiers are identified in the following table. Deviations from printf() are identified in italics.

Specifier Description Examples Types
d or i Decimal integer 392 INT64
o Octal 610
INT64*
x Hexadecimal integer 7fa
INT64*
X Hexadecimal integer (uppercase) 7FA
INT64*
f Decimal notation, in [-](integer part).(fractional part) for finite values, and in lowercase for non-finite values 392.650000
inf
nan
NUMERIC
FLOAT64
F Decimal notation, in [-](integer part).(fractional part) for finite values, and in uppercase for non-finite values 392.650000
INF
NAN
NUMERIC
FLOAT64
e Scientific notation (mantissa/exponent), lowercase 3.926500e+02
inf
nan
NUMERIC
FLOAT64
E Scientific notation (mantissa/exponent), uppercase 3.926500E+02
INF
NAN
NUMERIC
FLOAT64
g Either decimal notation or scientific notation, depending on the input value's exponent and the specified precision. Lowercase. See %g and %G behavior for details. 392.65
3.9265e+07
inf
nan
NUMERIC
FLOAT64
G Either decimal notation or scientific notation, depending on the input value's exponent and the specified precision. Uppercase. See %g and %G behavior for details. 392.65
3.9265E+07
INF
NAN
NUMERIC
FLOAT64
s String of characters sample STRING
t Returns a printable string representing the value. Often looks similar to casting the argument to STRING. See %t and %T behavior. sample
2014‑01‑01
<any>
T Produces a string that is a valid BigQuery constant with a similar type to the value's type (maybe wider, or maybe string). See %t and %T behavior. 'sample'
b'bytes sample'
1234
2.3
date '2014‑01‑01'
<any>
% '%%' produces a single '%' % n/a

*The specifiers %o, %x, and %X raise an error if negative values are used.

The format specifier can optionally contain the sub-specifiers identified above in the specifier prototype.

These sub-specifiers must comply with the following specifications.

Flags
Flags Description
- Left-justify within the given field width; Right justification is the default (see width sub-specifier)
+ Forces to precede the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign
<space> If no sign is going to be written, a blank space is inserted before the value
#
  • For `%o`, `%x`, and `%X`, this flag means to precede the value with 0, 0x or 0X respectively for values different than zero.
  • For `%f`, `%F`, `%e`, and `%E`, this flag means to add the decimal point even when there is no fractional part, unless the value is non-finite.
  • For `%g` and `%G`, this flag means to add the decimal point even when there is no fractional part unless the value is non-finite, and never remove the trailing zeros after the decimal point.
0 Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier)
'

Formats integers using the appropriating grouping character. For example:

  • FORMAT("%'d", 12345678) returns 12,345,678
  • FORMAT("%'x", 12345678) returns bc:614e
  • FORMAT("%'o", 55555) returns 15,4403
  • This flag is only relevant for decimal, hex, and octal values.

Flags may be specified in any order. Duplicate flags are not an error. When flags are not relevant for some element type, they are ignored.

Width
Width Description
<number> Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger
* The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted
Precision
Precision Description
.<number>
  • For integer specifiers `%d`, `%i`, `%o`, `%u`, `%x`, and `%X`: precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with trailing zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0.
  • For specifiers `%a`, `%A`, `%e`, `%E`, `%f`, and `%F`: this is the number of digits to be printed after the decimal point. The default value is 6.
  • For specifiers `%g` and `%G`: this is the number of significant digits to be printed, before the removal of the trailing zeros after the decimal point. The default value is 6.
.* The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted

%g and %G behavior

The %g and %G format specifiers choose either the decimal notation (like the %f and %F specifiers) or the scientific notation (like the %e and %E specifiers), depending on the input value's exponent and the specified precision.

Let p stand for the specified precision (defaults to 6; 1 if the specified precision is less than 1). The input value is first converted to scientific notation with precision = (p - 1). If the resulting exponent part x is less than -4 or no less than p, the scientific notation with precision = (p - 1) is used; otherwise the decimal notation with precision = (p - 1 - x) is used.

Unless # flag is present, the trailing zeros after the decimal point are removed, and the decimal point is also removed if there is no digit after it.

%t and %T behavior

The %t and %T format specifiers are defined for all types. The width, precision, and flags act as they do for %s: the width is the minimum width and the STRING will be padded to that size, and precision is the maximum width of content to show and the STRING will be truncated to that size, prior to padding to width.

The %t specifier is always meant to be a readable form of the value.

The %T specifier is always a valid SQL literal of a similar type, such as a wider numeric type. The literal will not include casts or a type name, except for the special case of non-finite floating point values.

The STRING is formatted as follows:

Type %t %T
NULL of any type NULL NULL
INT64
123 123
NUMERIC 123.0 (always with .0) NUMERIC "123.0"
FLOAT64 123.0 (always with .0)
123e+10
inf
-inf
NaN
123.0 (always with .0)
123e+10
CAST("inf" AS <type>)
CAST("-inf" AS <type>)
CAST("nan" AS <type>)
STRING unquoted string value quoted string literal
BYTES unquoted escaped bytes
e.g. abc\x01\x02
quoted bytes literal
e.g. b"abc\x01\x02"
DATE 2011-02-03 DATE "2011-02-03"
TIMESTAMP 2011-02-03 04:05:06+00 TIMESTAMP "2011-02-03 04:05:06+00"
ARRAY [value, value, ...]
where values are formatted with %t
[value, value, ...]
where values are formatted with %T
STRUCT (value, value, ...)
where fields are formatted with %t
(value, value, ...)
where fields are formatted with %T

Special cases:
Zero fields: STRUCT()
One field: STRUCT(value)

Error conditions

If a format specifier is invalid, or is not compatible with the related argument type, or the wrong number or arguments are provided, then an error is produced. For example, the following <format_string> expressions are invalid:

FORMAT('%s', 1)
FORMAT('%')

NULL argument handling

A NULL format string results in a NULL output STRING. Any other arguments are ignored in this case.

The function generally produces a NULL value if a NULL argument is present. For example, FORMAT('%i', NULL_expression) produces a NULL STRING as output.

However, there are some exceptions: if the format specifier is %t or %T (both of which produce STRINGs that effectively match CAST and literal value semantics), a NULL value produces 'NULL' (without the quotes) in the result STRING. For example, the function:

FORMAT('00-%t-00', NULL_expression);

Returns

00-NULL-00

Additional semantic rules

FLOAT64 values can be +/-inf or NaN. When an argument has one of those values, the result of the format specifiers %f, %F, %e, %E, %g, %G, and %t are inf, -inf, or nan (or the same in uppercase) as appropriate. This is consistent with how BigQuery casts these values to STRING. For %T, BigQuery returns quoted strings for FLOAT64 values that don't have non-string literal representations.

FROM_BASE32

FROM_BASE32(string_expr)

Description

Converts the base32-encoded input string_expr into BYTES format. To convert BYTES to a base32-encoded STRING, use TO_BASE32.

Return type

BYTES

Example

SELECT FROM_BASE32('MFRGGZDF74======') AS byte_data;

-- Note that the result of FROM_BASE32 is of type BYTES, displayed as a base64-encoded string.
+-----------+
| byte_data |
+-----------+
| YWJjZGX/  |
+-----------+

FROM_BASE64

FROM_BASE64(string_expr)

Description

Converts the base64-encoded input string_expr into BYTES format. To convert BYTES to a base64-encoded STRING, use TO_BASE64.

Return type

BYTES

Example

SELECT FROM_BASE64('3q2+7w==') AS byte_data;

-- Note that the result of FROM_BASE64 is of type BYTES, displayed as a base64-encoded string.
+-----------+
| byte_data |
+-----------+
| 3q2+7w==  |
+-----------+

FROM_HEX

FROM_HEX(string)

Description

Converts a hexadecimal-encoded STRING into BYTES format. Returns an error if the input STRING contains characters outside the range (0..9, A..F, a..f). The lettercase of the characters does not matter. If the input STRING has an odd number of characters, the function acts as if the input has an additional leading 0. To convert BYTES to a hexadecimal-encoded STRING, use TO_HEX.

Return type

BYTES

Example

WITH Input AS (
  SELECT '00010203aaeeefff' AS hex_str UNION ALL
  SELECT '0AF' UNION ALL
  SELECT '666f6f626172'
)
SELECT hex_str, FROM_HEX(hex_str) AS bytes_str
FROM Input;

-- Note that the result of FROM_HEX is of type BYTES, displayed as a base64-encoded string.
+------------------+--------------+
| hex_str          | bytes_str    |
+------------------+--------------+
| 0AF              | AAECA6ru7/8= |
| 00010203aaeeefff | AK8=         |
| 666f6f626172     | Zm9vYmFy     |
+------------------+--------------+

INITCAP

INITCAP(value[, delimiters])

Description

Takes a STRING and returns it with the first character in each word in uppercase and all other characters in lowercase. Non-alphabetic characters remain the same.

delimiters is an optional string argument that is used to override the default set of characters used to separate words. If delimiters is not specified, it defaults to the following characters:
<whitespace> [ ] ( ) { } / | \ < > ! ? @ " ^ # $ & ~ _ , . : ; * % + -

If value or delimiters is NULL, the function returns NULL.

Return type

STRING

Examples

WITH example AS
(
  SELECT "Hello World-everyone!" AS value UNION ALL
  SELECT "tHe dog BARKS loudly+friendly" AS value UNION ALL
  SELECT "apples&oranges;&pears" AS value UNION ALL
  SELECT "καθίσματα ταινιών" AS value
)
SELECT value, INITCAP(value) AS initcap_value FROM example

+-------------------------------+-------------------------------+
| value                         | initcap_value                 |
+-------------------------------+-------------------------------+
| Hello World-everyone!         | Hello World-Everyone!         |
| tHe dog BARKS loudly+friendly | The Dog Barks Loudly+Friendly |
| apples&oranges;&pears         | Apples&Oranges;&Pears         |
| καθίσματα ταινιών             | Καθίσματα Ταινιών             |
+-------------------------------+-------------------------------+

WITH example AS
(
  SELECT "hello WORLD!" AS value, "" AS delimiters UNION ALL
  SELECT "καθίσματα ταιντιώ@ν" AS value, "τ@" AS delimiters UNION ALL
  SELECT "Apples1oranges2pears" AS value, "12" AS delimiters UNION ALL
  SELECT "tHisEisEaESentence" AS value, "E" AS delimiters
)
SELECT value, delimiters, INITCAP(value, delimiters) AS initcap_value FROM example;

+----------------------+------------+----------------------+
| value                | delimiters | initcap_value        |
+----------------------+------------+----------------------+
| hello WORLD!         |            | Hello world!         |
| καθίσματα ταιντιώ@ν  | τ@         | ΚαθίσματΑ τΑιντΙώ@Ν  |
| Apples1oranges2pears | 12         | Apples1Oranges2Pears |
| tHisEisEaESentence   | E          | ThisEIsEAESentence   |
+----------------------+------------+----------------------+

INSTR

INSTR(source_value, search_value[, position[, occurrence]])

Description

Returns the lowest 1-based index of search_value in source_value. 0 is returned when no match is found. source_value and search_value must be the same type, either STRING or BYTES.

If position is specified, the search starts at this position in source_value, otherwise it starts at the beginning of source_value. If position is negative, the function searches backwards from the end of source_value, with -1 indicating the last character. position cannot be 0.

If occurrence is specified, the search returns the position of a specific instance of search_value in source_value, otherwise it returns the index of the first occurrence. If occurrence is greater than the number of matches found, 0 is returned. For occurrence > 1, the function searches for overlapping occurrences, in other words, the function searches for additional occurrences beginning with the second character in the previous occurrence. occurrence cannot be 0 or negative.

Return type

INT64

Examples

WITH example AS
(SELECT 'banana' as source_value, 'an' as search_value, 1 as position, 1 as
occurrence UNION ALL
SELECT 'banana' as source_value, 'an' as search_value, 1 as position, 2 as
occurrence UNION ALL
SELECT 'banana' as source_value, 'an' as search_value, 1 as position, 3 as
occurrence UNION ALL
SELECT 'banana' as source_value, 'an' as search_value, 3 as position, 1 as
occurrence UNION ALL
SELECT 'banana' as source_value, 'an' as search_value, -1 as position, 1 as
occurrence UNION ALL
SELECT 'banana' as source_value, 'an' as search_value, -3 as position, 1 as
occurrence UNION ALL
SELECT 'banana' as source_value, 'ann' as search_value, 1 as position, 1 as
occurrence UNION ALL
SELECT 'helloooo' as source_value, 'oo' as search_value, 1 as position, 1 as
occurrence UNION ALL
SELECT 'helloooo' as source_value, 'oo' as search_value, 1 as position, 2 as
occurrence
)
SELECT source_value, search_value, position, occurrence, INSTR(source_value,
search_value, position, occurrence) AS instr
FROM example;

+--------------+--------------+----------+------------+-------+
| source_value | search_value | position | occurrence | instr |
+--------------+--------------+----------+------------+-------+
| banana       | an           | 1        | 1          | 2     |
| banana       | an           | 1        | 2          | 4     |
| banana       | an           | 1        | 3          | 0     |
| banana       | an           | 3        | 1          | 4     |
| banana       | an           | -1       | 1          | 4     |
| banana       | an           | -3       | 1          | 4     |
| banana       | ann          | 1        | 1          | 0     |
| helloooo     | oo           | 1        | 1          | 5     |
| helloooo     | oo           | 1        | 2          | 6     |
+--------------+--------------+----------+------------+-------+

LEFT

LEFT(value, length)

Description

Returns a STRING or BYTES value that consists of the specified number of leftmost characters or bytes from value. The length is an INT64 that specifies the length of the returned value. If value is of type BYTES, length is the number of leftmost bytes to return. If value is STRING, length is the number of leftmost characters to return.

If length is 0, an empty STRING or BYTES value will be returned. If length is negative, an error will be returned. If length exceeds the number of characters or bytes from value, the original value will be returned.

Return type

STRING or BYTES

Examples

WITH examples AS
(SELECT 'apple' as example
UNION ALL
SELECT 'banana' as example
UNION ALL
SELECT 'абвгд' as example
)
SELECT example, LEFT(example, 3) AS left_example
FROM examples;

+---------+--------------+
| example | left_example |
+---------+--------------+
| apple   | app          |
| banana  | ban          |
| абвгд   | абв          |
+---------+--------------+
WITH examples AS
(SELECT b'apple' as example
UNION ALL
SELECT b'banana' as example
UNION ALL
SELECT b'\xab\xcd\xef\xaa\xbb' as example
)
SELECT example, LEFT(example, 3) AS left_example
FROM examples;

-- Note that the result of LEFT is of type BYTES, displayed as a base64-encoded string.
+----------+--------------+
| example  | left_example |
+----------+--------------+
| YXBwbGU= | YXBw         |
| YmFuYW5h | YmFu         |
| q83vqrs= | q83v         |
+----------+--------------+

LENGTH

LENGTH(value)

Description

Returns the length of the STRING or BYTES value. The returned value is in characters for STRING arguments and in bytes for the BYTES argument.

Return type

INT64

Examples


WITH example AS
  (SELECT "абвгд" AS characters)

SELECT
  characters,
  LENGTH(characters) AS string_example,
  LENGTH(CAST(characters AS BYTES)) AS bytes_example
FROM example;

+------------+----------------+---------------+
| characters | string_example | bytes_example |
+------------+----------------+---------------+
| абвгд      |              5 |            10 |
+------------+----------------+---------------+

LPAD

LPAD(original_value, return_length[, pattern])

Description

Returns a STRING or BYTES value that consists of original_value prepended with pattern. The return_length is an INT64 that specifies the length of the returned value. If original_value is of type BYTES, return_length is the number of bytes. If original_value is of type STRING, return_length is the number of characters.

The default value of pattern is a blank space.

Both original_value and pattern must be the same data type.

If return_length is less than or equal to the original_value length, this function returns the original_value value, truncated to the value of return_length. For example, LPAD("hello world", 7); returns "hello w".

If original_value, return_length, or pattern is NULL, this function returns NULL.

This function returns an error if:

  • return_length is negative
  • pattern is empty

Return type

STRING or BYTES

Examples

SELECT t, len, FORMAT("%T", LPAD(t, len)) AS LPAD FROM UNNEST([
  STRUCT('abc' AS t, 5 AS len),
  ('abc', 2),
  ('例子', 4)
]);

+------+-----+----------+
| t    | len | LPAD     |
|------|-----|----------|
| abc  | 5   | "  abc"  |
| abc  | 2   | "ab"     |
| 例子  | 4   | "  例子" |
+------+-----+----------+
SELECT t, len, pattern, FORMAT("%T", LPAD(t, len, pattern)) AS LPAD FROM UNNEST([
  STRUCT('abc' AS t, 8 AS len, 'def' AS pattern),
  ('abc', 5, '-'),
  ('例子', 5, '中文')
]);

+------+-----+---------+--------------+
| t    | len | pattern | LPAD         |
|------|-----|---------|--------------|
| abc  | 8   | def     | "defdeabc"   |
| abc  | 5   | -       | "--abc"      |
| 例子  | 5   | 中文    | "中文中例子"   |
+------+-----+---------+--------------+
SELECT FORMAT("%T", t) AS t, len, FORMAT("%T", LPAD(t, len)) AS LPAD FROM UNNEST([
  STRUCT(b'abc' AS t, 5 AS len),
  (b'abc', 2),
  (b'\xab\xcd\xef', 4)
]);

+-----------------+-----+------------------+
| t               | len | LPAD             |
|-----------------|-----|------------------|
| b"abc"          | 5   | b"  abc"         |
| b"abc"          | 2   | b"ab"            |
| b"\xab\xcd\xef" | 4   | b" \xab\xcd\xef" |
+-----------------+-----+------------------+
SELECT
  FORMAT("%T", t) AS t,
  len,
  FORMAT("%T", pattern) AS pattern,
  FORMAT("%T", LPAD(t, len, pattern)) AS LPAD
FROM UNNEST([
  STRUCT(b'abc' AS t, 8 AS len, b'def' AS pattern),
  (b'abc', 5, b'-'),
  (b'\xab\xcd\xef', 5, b'\x00')
]);

+-----------------+-----+---------+-------------------------+
| t               | len | pattern | LPAD                    |
|-----------------|-----|---------|-------------------------|
| b"abc"          | 8   | b"def"  | b"defdeabc"             |
| b"abc"          | 5   | b"-"    | b"--abc"                |
| b"\xab\xcd\xef" | 5   | b"\x00" | b"\x00\x00\xab\xcd\xef" |
+-----------------+-----+---------+-------------------------+

LOWER

LOWER(value)

Description

For STRING arguments, returns the original string with all alphabetic characters in lowercase. Mapping between lowercase and uppercase is done according to the Unicode Character Database without taking into account language-specific mappings.

For BYTES arguments, the argument is treated as ASCII text, with all bytes greater than 127 left intact.

Return type

STRING or BYTES

Examples


WITH items AS
  (SELECT
    "FOO" as item
  UNION ALL
  SELECT
    "BAR" as item
  UNION ALL
  SELECT
    "BAZ" as item)

SELECT
  LOWER(item) AS example
FROM items;

+---------+
| example |
+---------+
| foo     |
| bar     |
| baz     |
+---------+

LTRIM

LTRIM(value1[, value2])

Description

Identical to TRIM, but only removes leading characters.

Return type

STRING or BYTES

Examples

WITH items AS
  (SELECT "   apple   " as item
  UNION ALL
  SELECT "   banana   " as item
  UNION ALL
  SELECT "   orange   " as item)

SELECT
  CONCAT("#", LTRIM(item), "#") as example
FROM items;

+-------------+
| example     |
+-------------+
| #apple   #  |
| #banana   # |
| #orange   # |
+-------------+
WITH items AS
  (SELECT "***apple***" as item
  UNION ALL
  SELECT "***banana***" as item
  UNION ALL
  SELECT "***orange***" as item)

SELECT
  LTRIM(item, "*") as example
FROM items;

+-----------+
| example   |
+-----------+
| apple***  |
| banana*** |
| orange*** |
+-----------+
WITH items AS
  (SELECT "xxxapplexxx" as item
  UNION ALL
  SELECT "yyybananayyy" as item
  UNION ALL
  SELECT "zzzorangezzz" as item
  UNION ALL
  SELECT "xyzpearxyz" as item)
SELECT
  LTRIM(item, "xyz") as example
FROM items;

+-----------+
| example   |
+-----------+
| applexxx  |
| bananayyy |
| orangezzz |
| pearxyz   |
+-----------+

NORMALIZE

NORMALIZE(value[, normalization_mode])

Description

Takes a string value and returns it as a normalized string.

Normalization is used to ensure that two strings are equivalent. Normalization is often used in situations in which two strings render the same on the screen but have different Unicode code points.

NORMALIZE supports four optional normalization modes:

Value Name Description
NFC Normalization Form Canonical Composition Decomposes and recomposes characters by canonical equivalence.
NFKC Normalization Form Compatibility Composition Decomposes characters by compatibility, then recomposes them by canonical equivalence.
NFD Normalization Form Canonical Decomposition Decomposes characters by canonical equivalence, and multiple combining characters are arranged in a specific order.
NFKD Normalization Form Compatibility Decomposition Decomposes characters by compatibility, and multiple combining characters are arranged in a specific order.

The default normalization mode is NFC.

Return type

STRING

Examples

SELECT a, b, a = b as normalized
FROM (SELECT NORMALIZE('\u00ea') as a, NORMALIZE('\u0065\u0302') as b)
AS normalize_example;

+---+---+------------+
| a | b | normalized |
+---+---+------------+
| ê | ê | true       |
+---+---+------------+

The following example normalizes different space characters.

WITH EquivalentNames AS (
  SELECT name
  FROM UNNEST([
      'Jane\u2004Doe',
      'John\u2004Smith',
      'Jane\u2005Doe',
      'Jane\u2006Doe',
      'John Smith']) AS name
)
SELECT
  NORMALIZE(name, NFKC) AS normalized_name,
  COUNT(*) AS name_count
FROM EquivalentNames
GROUP BY 1;

+-----------------+------------+
| normalized_name | name_count |
+-----------------+------------+
| John Smith      | 2          |
| Jane Doe        | 3          |
+-----------------+------------+

NORMALIZE_AND_CASEFOLD

NORMALIZE_AND_CASEFOLD(value[, normalization_mode])

Description

Takes a STRING, value, and performs the same actions as NORMALIZE, as well as casefolding for case-insensitive operations.

NORMALIZE_AND_CASEFOLD supports four optional normalization modes:

Value Name Description
NFC Normalization Form Canonical Composition Decomposes and recomposes characters by canonical equivalence.
NFKC Normalization Form Compatibility Composition Decomposes characters by compatibility, then recomposes them by canonical equivalence.
NFD Normalization Form Canonical Decomposition Decomposes characters by canonical equivalence, and multiple combining characters are arranged in a specific order.
NFKD Normalization Form Compatibility Decomposition Decomposes characters by compatibility, and multiple combining characters are arranged in a specific order.

The default normalization mode is NFC.

Return type

STRING

Example

WITH Strings AS (
  SELECT '\u2168' AS a, 'IX' AS b UNION ALL
  SELECT '\u0041\u030A', '\u00C5'
)
SELECT a, b,
  NORMALIZE_AND_CASEFOLD(a, NFD)=NORMALIZE_AND_CASEFOLD(b, NFD) AS nfd,
  NORMALIZE_AND_CASEFOLD(a, NFC)=NORMALIZE_AND_CASEFOLD(b, NFC) AS nfc,
  NORMALIZE_AND_CASEFOLD(a, NFKD)=NORMALIZE_AND_CASEFOLD(b, NFKD) AS nkfd,
  NORMALIZE_AND_CASEFOLD(a, NFKC)=NORMALIZE_AND_CASEFOLD(b, NFKC) AS nkfc
FROM Strings;

+---+----+-------+-------+------+------+
| a | b  | nfd   | nfc   | nkfd | nkfc |
+---+----+-------+-------+------+------+
| Ⅸ | IX | false | false | true | true |
| Å | Å  | true  | true  | true | true |
+---+----+-------+-------+------+------+

OCTET_LENGTH

OCTET_LENGTH(value)

Alias for BYTE_LENGTH.

REGEXP_CONTAINS

REGEXP_CONTAINS(value, regexp)

Description

Returns TRUE if value is a partial match for the regular expression, regexp.

If the regexp argument is invalid, the function returns an error.

You can search for a full match by using ^ (beginning of text) and $ (end of text). Due to regular expression operator precedence, it is good practice to use parentheses around everything between ^ and $.

Return type

BOOL

Examples

SELECT
  email,
  REGEXP_CONTAINS(email, r"@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+") AS is_valid
FROM
  (SELECT
    ["foo@example.com", "bar@example.org", "www.example.net"]
    AS addresses),
  UNNEST(addresses) AS email;

+-----------------+----------+
| email           | is_valid |
+-----------------+----------+
| foo@example.com | true     |
| bar@example.org | true     |
| www.example.net | false    |
+-----------------+----------+

# Performs a full match, using ^ and $. Due to regular expression operator
# precedence, it is good practice to use parentheses around everything between ^
# and $.
SELECT
  email,
  REGEXP_CONTAINS(email, r"^([\w.+-]+@foo\.com|[\w.+-]+@bar\.org)$")
    AS valid_email_address,
  REGEXP_CONTAINS(email, r"^[\w.+-]+@foo\.com|[\w.+-]+@bar\.org$")
    AS without_parentheses
FROM
  (SELECT
    ["a@foo.com", "a@foo.computer", "b@bar.org", "!b@bar.org", "c@buz.net"]
    AS addresses),
  UNNEST(addresses) AS email;

+----------------+---------------------+---------------------+
| email          | valid_email_address | without_parentheses |
+----------------+---------------------+---------------------+
| a@foo.com      | true                | true                |
| a@foo.computer | false               | true                |
| b@bar.org      | true                | true                |
| !b@bar.org     | false               | true                |
| c@buz.net      | false               | false               |
+----------------+---------------------+---------------------+

REGEXP_EXTRACT

REGEXP_EXTRACT(value, regexp[, position[, occurrence]])

Description

Returns the substring in value that matches the regular expression, regexp. Returns NULL if there is no match.

If the regular expression contains a capturing group, the function returns the substring that is matched by that capturing group. If the expression does not contain a capturing group, the function returns the entire matching substring.

If position is specified, the search starts at this position in value, otherwise it starts at the beginning of value. The position must be a positive integer and cannot be 0. If position is greater than the length of value, NULL is returned.

If occurrence is specified, the search returns a specific occurrence of the regexp in value, otherwise returns the first match. If occurrence is greater than the number of matches found, NULL is returned. For occurrence > 1, the function searches for additional occurrences beginning with the character following the previous occurrence.

Returns an error if:

  • The regular expression is invalid
  • The regular expression has more than one capturing group
  • The position is not a positive integer
  • The occurrence is not a positive integer

Return type

STRING or BYTES

Examples

WITH email_addresses AS
  (SELECT "foo@example.com" as email
  UNION ALL
  SELECT "bar@example.org" as email
  UNION ALL
  SELECT "baz@example.net" as email)

SELECT
  REGEXP_EXTRACT(email, r"^[a-zA-Z0-9_.+-]+")
  AS user_name
FROM email_addresses;

+-----------+
| user_name |
+-----------+
| foo       |
| bar       |
| baz       |
+-----------+
WITH email_addresses AS
  (SELECT "foo@example.com" as email
  UNION ALL
  SELECT "bar@example.org" as email
  UNION ALL
  SELECT "baz@example.net" as email)

SELECT
  REGEXP_EXTRACT(email, r"^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.([a-zA-Z0-9-.]+$)")
  AS top_level_domain
FROM email_addresses;

+------------------+
| top_level_domain |
+------------------+
| com              |
| org              |
| net              |
+------------------+
WITH example AS
(SELECT 'Hello Helloo and Hellooo' AS value, 'H?ello+' AS regex, 1 as position,
1 AS occurrence UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 1, 2 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 1, 3 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 1, 4 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 2, 1 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 3, 1 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 3, 2 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 3, 3 UNION ALL
SELECT 'Hello Helloo and Hellooo', 'H?ello+', 20, 1 UNION ALL
SELECT 'cats&dogs&rabbits' ,'\\w+&', 1, 2 UNION ALL
SELECT 'cats&dogs&rabbits', '\\w+&', 2, 3
)
SELECT value, regex, position, occurrence, REGEXP_EXTRACT(value, regex,
position, occurrence) AS regexp_value FROM example;

+--------------------------+---------+----------+------------+--------------+
| value                    | regex   | position | occurrence | regexp_value |
+--------------------------+---------+----------+------------+--------------+
| Hello Helloo and Hellooo | H?ello+ | 1        | 1          | Hello        |
| Hello Helloo and Hellooo | H?ello+ | 1        | 2          | Helloo       |
| Hello Helloo and Hellooo | H?ello+ | 1        | 3          | Hellooo      |
| Hello Helloo and Hellooo | H?ello+ | 1        | 4          | NULL         |
| Hello Helloo and Hellooo | H?ello+ | 2        | 1          | ello         |
| Hello Helloo and Hellooo | H?ello+ | 3        | 1          | Helloo       |
| Hello Helloo and Hellooo | H?ello+ | 3        | 2          | Hellooo      |
| Hello Helloo and Hellooo | H?ello+ | 3        | 3          | NULL         |
| Hello Helloo and Hellooo | H?ello+ | 20       | 1          | NULL         |
| cats&dogs&rabbits        | \w+&    | 1        | 2          | dogs&        |
| cats&dogs&rabbits        | \w+&    | 2        | 3          | NULL         |
+--------------------------+---------+----------+------------+--------------+

REGEXP_EXTRACT_ALL

REGEXP_EXTRACT_ALL(value, regexp)

Description

Returns an array of all substrings of value that match the regular expression, regexp.

The REGEXP_EXTRACT_ALL function only returns non-overlapping matches. For example, using this function to extract ana from banana returns only one substring, not two.

Return type

An ARRAY of either STRINGs or BYTES

Examples

WITH code_markdown AS
  (SELECT "Try `function(x)` or `function(y)`" as code)

SELECT
  REGEXP_EXTRACT_ALL(code, "`(.+?)`") AS example
FROM code_markdown;

+----------------------------+
| example                    |
+----------------------------+
| [function(x), function(y)] |
+----------------------------+

REGEXP_INSTR

REGEXP_INSTR(source_value, regexp [, position[, occurrence, [occurrence_position]]])

Description

Returns the lowest 1-based index of a regular expression, regexp, in source_value. Returns 0 when no match is found or the regular expression is empty. Returns an error if the regular expression is invalid or has more than one capturing group. source_value and regexp must be the same type, either STRING or BYTES.

If position is specified, the search starts at this position in source_value, otherwise it starts at the beginning of source_value. If position is negative, the function searches backwards from the end of source_value, with -1 indicating the last character. position cannot be 0.

If occurrence is specified, the search returns the position of a specific instance of regexp in source_value, otherwise it returns the index of the first occurrence. If occurrence is greater than the number of matches found, 0 is returned. For occurrence > 1, the function searches for overlapping occurrences, in other words, the function searches for additional occurrences beginning with the second character in the previous occurrence. occurrence cannot be 0 or negative.

You can optionally use occurrence_position to specify where a position in relation to an occurrence starts. Your choices are: + 0: Returns the beginning position of the occurrence. + 1: Returns the first position following the end of the occurrence. If the end of the occurrence is also the end of the input, one off the end of the occurrence is returned. For example, length of a string + 1.

Return type

INT64

Examples

WITH example AS (
  SELECT 'ab@gmail.com' AS source_value, '@[^.]*' AS regexp UNION ALL
  SELECT 'ab@mail.com', '@[^.]*' UNION ALL
  SELECT 'abc@gmail.com', '@[^.]*' UNION ALL
  SELECT 'abc.com', '@[^.]*')
SELECT source_value, regexp, REGEXP_INSTR(source_value, regexp) AS instr
FROM example;

+---------------+--------+-------+
| source_value  | regexp | instr |
+---------------+--------+-------+
| ab@gmail.com  | @[^.]* | 3     |
| ab@mail.com   | @[^.]* | 3     |
| abc@gmail.com | @[^.]* | 4     |
| abc.com       | @[^.]* | 0     |
+---------------+--------+-------+
WITH example AS (
  SELECT 'a@gmail.com b@gmail.com' AS source_value, '@[^.]*' AS regexp, 1 AS position UNION ALL
  SELECT 'a@gmail.com b@gmail.com', '@[^.]*', 2 UNION ALL
  SELECT 'a@gmail.com b@gmail.com', '@[^.]*', 3 UNION ALL
  SELECT 'a@gmail.com b@gmail.com', '@[^.]*', 4)
SELECT
  source_value, regexp, position,
  REGEXP_INSTR(source_value, regexp, position) AS instr
FROM example;

+-------------------------+--------+----------+-------+
| source_value            | regexp | position | instr |
+-------------------------+--------+----------+-------+
| a@gmail.com b@gmail.com | @[^.]* | 1        | 2     |
| a@gmail.com b@gmail.com | @[^.]* | 2        | 2     |
| a@gmail.com b@gmail.com | @[^.]* | 3        | 14    |
| a@gmail.com b@gmail.com | @[^.]* | 4        | 14    |
+-------------------------+--------+----------+-------+
WITH example AS (
  SELECT 'a@gmail.com b@gmail.com c@gmail.com' AS source_value,
         '@[^.]*' AS regexp, 1 AS position, 1 AS occurrence UNION ALL
  SELECT 'a@gmail.com b@gmail.com c@gmail.com', '@[^.]*', 1, 2 UNION ALL
  SELECT 'a@gmail.com b@gmail.com c@gmail.com', '@[^.]*', 1, 3)
SELECT
  source_value, regexp, position, occurrence,
  REGEXP_INSTR(source_value, regexp, position, occurrence) AS instr
FROM example;

+-------------------------------------+--------+----------+------------+-------+
| source_value                        | regexp | position | occurrence | instr |
+-------------------------------------+--------+----------+------------+-------+
| a@gmail.com b@gmail.com c@gmail.com | @[^.]* | 1        | 1          | 2     |
| a@gmail.com b@gmail.com c@gmail.com | @[^.]* | 1        | 2          | 14    |
| a@gmail.com b@gmail.com c@gmail.com | @[^.]* | 1        | 3          | 26    |
+-------------------------------------+--------+----------+------------+-------+
WITH example AS (
  SELECT 'a@gmail.com' AS source_value, '@[^.]*' AS regexp,
         1 AS position, 1 AS occurrence, 0 AS o_position UNION ALL
  SELECT 'a@gmail.com', '@[^.]*', 1, 1, 1)
SELECT
  source_value, regexp, position, occurrence, o_position,
  REGEXP_INSTR(source_value, regexp, position, occurrence, o_position) AS instr
FROM example;

+--------------+--------+----------+------------+------------+-------+
| source_value | regexp | position | occurrence | o_position | instr |
+--------------+--------+----------+------------+------------+-------+
| a@gmail.com  | @[^.]* | 1        | 1          | 0          | 2     |
| a@gmail.com  | @[^.]* | 1        | 1          | 1          | 8     |
+--------------+--------+----------+------------+------------+-------+

REGEXP_REPLACE

REGEXP_REPLACE(value, regexp, replacement)

Description

Returns a STRING where all substrings of value that match regular expression regexp are replaced with replacement.

You can use backslashed-escaped digits (\1 to \9) within the replacement argument to insert text matching the corresponding parenthesized group in the regexp pattern. Use \0 to refer to the entire matching text.

The REGEXP_REPLACE function only replaces non-overlapping matches. For example, replacing ana within banana results in only one replacement, not two.

If the regexp argument is not a valid regular expression, this function returns an error.

Return type

STRING or BYTES

Examples

WITH markdown AS
  (SELECT "# Heading" as heading
  UNION ALL
  SELECT "# Another heading" as heading)

SELECT
  REGEXP_REPLACE(heading, r"^# ([a-zA-Z0-9\s]+$)", "<h1>\\1</h1>")
  AS html
FROM markdown;

+--------------------------+
| html                     |
+--------------------------+
| <h1>Heading</h1>         |
| <h1>Another heading</h1> |
+--------------------------+

REGEXP_SUBSTR

REGEXP_SUBSTR(value, regexp[, position[, occurrence]])

Description

Synonym for REGEXP_EXTRACT.

Return type

STRING or BYTES

Examples

WITH example AS
(SELECT 'Hello World Helloo' AS value, 'H?ello+' AS regex, 1 AS position, 1 AS
occurrence
)
SELECT value, regex, position, occurrence, REGEXP_SUBSTR(value, regex,
position, occurrence) AS regexp_value FROM example;

+--------------------+---------+----------+------------+--------------+
| value              | regex   | position | occurrence | regexp_value |
+--------------------+---------+----------+------------+--------------+
| Hello World Helloo | H?ello+ | 1        | 1          | Hello        |
+--------------------+---------+----------+------------+--------------+

REPLACE

REPLACE(original_value, from_value, to_value)

Description

Replaces all occurrences of from_value with to_value in original_value. If from_value is empty, no replacement is made.

Return type

STRING or BYTES

Examples

WITH desserts AS
  (SELECT "apple pie" as dessert
  UNION ALL
  SELECT "blackberry pie" as dessert
  UNION ALL
  SELECT "cherry pie" as dessert)

SELECT
  REPLACE (dessert, "pie", "cobbler") as example
FROM desserts;

+--------------------+
| example            |
+--------------------+
| apple cobbler      |
| blackberry cobbler |
| cherry cobbler     |
+--------------------+

REPEAT

REPEAT(original_value, repetitions)

Description

Returns a STRING or BYTES value that consists of original_value, repeated. The repetitions parameter specifies the number of times to repeat original_value. Returns NULL if either original_value or repetitions are NULL.

This function returns an error if the repetitions value is negative.

Return type

STRING or BYTES

Examples

SELECT t, n, REPEAT(t, n) AS REPEAT FROM UNNEST([
  STRUCT('abc' AS t, 3 AS n),
  ('例子', 2),
  ('abc', null),
  (null, 3)
]);

+------+------+-----------+
| t    | n    | REPEAT    |
|------|------|-----------|
| abc  | 3    | abcabcabc |
| 例子 | 2    | 例子例子  |
| abc  | NULL | NULL      |
| NULL | 3    | NULL      |
+------+------+-----------+

REVERSE

REVERSE(value)

Description

Returns the reverse of the input STRING or BYTES.

Return type

STRING or BYTES

Examples

WITH example AS (
  SELECT "foo" AS sample_string, b"bar" AS sample_bytes UNION ALL
  SELECT "абвгд" AS sample_string, b"123" AS sample_bytes
)
SELECT
  sample_string,
  REVERSE(sample_string) AS reverse_string,
  sample_bytes,
  REVERSE(sample_bytes) AS reverse_bytes
FROM example;

+---------------+----------------+--------------+---------------+
| sample_string | reverse_string | sample_bytes | reverse_bytes |
+---------------+----------------+--------------+---------------+
| foo           | oof            | bar          | rab           |
| абвгд         | дгвба          | 123          | 321           |
+---------------+----------------+--------------+---------------+
RIGHT(value, length)

Description

Returns a STRING or BYTES value that consists of the specified number of rightmost characters or bytes from value. The length is an INT64 that specifies the length of the returned value. If value is BYTES, length is the number of rightmost bytes to return. If value is STRING, length is the number of rightmost characters to return.

If length is 0, an empty STRING or BYTES value will be returned. If length is negative, an error will be returned. If length exceeds the number of characters or bytes from value, the original value will be returned.

Return type

STRING or BYTES

Examples

WITH examples AS
(SELECT 'apple' as example
UNION ALL
SELECT 'banana' as example
UNION ALL
SELECT 'абвгд' as example
)
SELECT example, RIGHT(example, 3) AS right_example
FROM examples;

+---------+---------------+
| example | right_example |
+---------+---------------+
| apple   | ple           |
| banana  | ana           |
| абвгд   | вгд           |
+---------+---------------+
WITH examples AS
(SELECT b'apple' as example
UNION ALL
SELECT b'banana' as example
UNION ALL
SELECT b'\xab\xcd\xef\xaa\xbb' as example
)
SELECT example, RIGHT(example, 3) AS right_example
FROM examples;

-- Note that the result of RIGHT is of type BYTES, displayed as a base64-encoded string.
+----------+---------------+
| example  | right_example |
+----------+---------------+
| YXBwbGU= | cGxl          |
| YmFuYW5h | YW5h          |
| q83vqrs= | 76q7          |
+----------+---------------+

RPAD

RPAD(original_value, return_length[, pattern])

Description

Returns a STRING or BYTES value that consists of original_value appended with pattern. The return_length parameter is an INT64 that specifies the length of the returned value. If original_value is BYTES, return_length is the number of bytes. If original_value is STRING, return_length is the number of characters.

The default value of pattern is a blank space.

Both original_value and pattern must be the same data type.

If return_length is less than or equal to the original_value length, this function returns the original_value value, truncated to the value of return_length. For example, RPAD("hello world", 7); returns "hello w".

If original_value, return_length, or pattern is NULL, this function returns NULL.

This function returns an error if:

  • return_length is negative
  • pattern is empty

Return type

STRING or BYTES

Examples

SELECT t, len, FORMAT("%T", RPAD(t, len)) AS RPAD FROM UNNEST([
  STRUCT('abc' AS t, 5 AS len),
  ('abc', 2),
  ('例子', 4)
]);

+------+-----+----------+
| t    | len | RPAD     |
|------|-----|----------|
| abc  | 5   | "abc  "  |
| abc  | 2   | "ab"     |
| 例子  | 4   | "例子  " |
+------+-----+----------+
SELECT t, len, pattern, FORMAT("%T", RPAD(t, len, pattern)) AS RPAD FROM UNNEST([
  STRUCT('abc' AS t, 8 AS len, 'def' AS pattern),
  ('abc', 5, '-'),
  ('例子', 5, '中文')
]);

+------+-----+---------+--------------+
| t    | len | pattern | RPAD         |
|------|-----|---------|--------------|
| abc  | 8   | def     | "abcdefde"   |
| abc  | 5   | -       | "abc--"      |
| 例子  | 5   | 中文     | "例子中文中"  |
+------+-----+---------+--------------+
SELECT FORMAT("%T", t) AS t, len, FORMAT("%T", RPAD(t, len)) AS RPAD FROM UNNEST([
  STRUCT(b'abc' AS t, 5 AS len),
  (b'abc', 2),
  (b'\xab\xcd\xef', 4)
]);

+-----------------+-----+------------------+
| t               | len | RPAD             |
|-----------------|-----|------------------|
| b"abc"          | 5   | b"abc  "         |
| b"abc"          | 2   | b"ab"            |
| b"\xab\xcd\xef" | 4   | b"\xab\xcd\xef " |
+-----------------+-----+------------------+
SELECT
  FORMAT("%T", t) AS t,
  len,
  FORMAT("%T", pattern) AS pattern,
  FORMAT("%T", RPAD(t, len, pattern)) AS RPAD
FROM UNNEST([
  STRUCT(b'abc' AS t, 8 AS len, b'def' AS pattern),
  (b'abc', 5, b'-'),
  (b'\xab\xcd\xef', 5, b'\x00')
]);

+-----------------+-----+---------+-------------------------+
| t               | len | pattern | RPAD                    |
|-----------------|-----|---------|-------------------------|
| b"abc"          | 8   | b"def"  | b"abcdefde"             |
| b"abc"          | 5   | b"-"    | b"abc--"                |
| b"\xab\xcd\xef" | 5   | b"\x00" | b"\xab\xcd\xef\x00\x00" |
+-----------------+-----+---------+-------------------------+

RTRIM

RTRIM(value1[, value2])

Description

Identical to TRIM, but only removes trailing characters.

Return type

STRING or BYTES

Examples

WITH items AS
  (SELECT "***apple***" as item
  UNION ALL
  SELECT "***banana***" as item
  UNION ALL
  SELECT "***orange***" as item)

SELECT
  RTRIM(item, "*") as example
FROM items;

+-----------+
| example   |
+-----------+
| ***apple  |
| ***banana |
| ***orange |
+-----------+
WITH items AS
  (SELECT "applexxx" as item
  UNION ALL
  SELECT "bananayyy" as item
  UNION ALL
  SELECT "orangezzz" as item
  UNION ALL
  SELECT "pearxyz" as item)

SELECT
  RTRIM(item, "xyz") as example
FROM items;

+---------+
| example |
+---------+
| apple   |
| banana  |
| orange  |
| pear    |
+---------+

SAFE_CONVERT_BYTES_TO_STRING

SAFE_CONVERT_BYTES_TO_STRING(value)

Description

Converts a sequence of BYTES to a STRING. Any invalid UTF-8 characters are replaced with the Unicode replacement character, U+FFFD.

Return type

STRING

Examples

The following statement returns the Unicode replacement character, �.

SELECT SAFE_CONVERT_BYTES_TO_STRING(b'\xc2') as safe_convert;

SOUNDEX

SOUNDEX(value)

Description

Returns a STRING that represents the Soundex code for value.

SOUNDEX produces a phonetic representation of a string. It indexes words by sound, as pronounced in English. It is typically used to help determine whether two strings, such as the family names Levine and Lavine, or the words to and too, have similar English-language pronunciation.

The result of the SOUNDEX consists of a letter followed by 3 digits. Non-latin characters are ignored. If the remaining string is empty after removing non-Latin characters, an empty STRING is returned.

Return type

STRING

Examples

WITH example AS (
  SELECT 'Ashcraft' AS value UNION ALL
  SELECT 'Raven' AS value UNION ALL
  SELECT 'Ribbon' AS value UNION ALL
  SELECT 'apple' AS value UNION ALL
  SELECT 'Hello world!' AS value UNION ALL
  SELECT '  H3##!@llo w00orld!' AS value UNION ALL
  SELECT '#1' AS value UNION ALL
  SELECT NULL AS value
)
SELECT value, SOUNDEX(value) AS soundex
FROM example;

+----------------------+---------+
| value                | soundex |
+----------------------+---------+
| Ashcraft             | A261    |
| Raven                | R150    |
| Ribbon               | R150    |
| apple                | a140    |
| Hello world!         | H464    |
|   H3##!@llo w00orld! | H464    |
| #1                   |         |
| NULL                 | NULL    |
+----------------------+---------+

SPLIT

SPLIT(value[, delimiter])

Description

Splits value using the delimiter argument.

For STRING, the default delimiter is the comma ,.

For BYTES, you must specify a delimiter.

Splitting on an empty delimiter produces an array of UTF-8 characters for STRING values, and an array of BYTES for BYTES values.

Splitting an empty STRING returns an ARRAY with a single empty STRING.

Return type

ARRAY of type STRING or ARRAY of type BYTES

Examples

WITH letters AS
  (SELECT "" as letter_group
  UNION ALL
  SELECT "a" as letter_group
  UNION ALL
  SELECT "b c d" as letter_group)

SELECT SPLIT(letter_group, " ") as example
FROM letters;

+----------------------+
| example              |
+----------------------+
| []                   |
| [a]                  |
| [b, c, d]            |
+----------------------+

STARTS_WITH

STARTS_WITH(value1, value2)

Description

Takes two STRING or BYTES values. Returns TRUE if the second value is a prefix of the first.

Return type

BOOL

Examples

WITH items AS
  (SELECT "foo" as item
  UNION ALL
  SELECT "bar" as item
  UNION ALL
  SELECT "baz" as item)

SELECT
  STARTS_WITH(item, "b") as example
FROM items;

+---------+
| example |
+---------+
|   False |
|    True |
|    True |
+---------+

STRPOS

STRPOS(string, substring)

Description

Returns the 1-based index of the first occurrence of substring inside string. Returns 0 if substring is not found.

Return type

INT64

Examples

WITH email_addresses AS
  (SELECT
    "foo@example.com" AS email_address
  UNION ALL
  SELECT
    "foobar@example.com" AS email_address
  UNION ALL
  SELECT
    "foobarbaz@example.com" AS email_address
  UNION ALL
  SELECT
    "quxexample.com" AS email_address)

SELECT
  STRPOS(email_address, "@") AS example
FROM email_addresses;

+---------+
| example |
+---------+
|       4 |
|       7 |
|      10 |
|       0 |
+---------+

SUBSTR

SUBSTR(value, position[, length])

Description

Returns a substring of the supplied STRING or BYTES value. The position argument is an integer specifying the starting position of the substring, with position = 1 indicating the first character or byte. The length argument is the maximum number of characters for STRING arguments, or bytes for BYTES arguments.

If position is negative, the function counts from the end of value, with -1 indicating the last character.

If position is a position off the left end of the STRING (position = 0 or position < -LENGTH(value)), the function starts from position = 1. If length exceeds the length of value, the function returns fewer than length characters.

If length is less than 0, the function returns an error.

Return type

STRING or BYTES

Examples

WITH items AS
  (SELECT "apple" as item
  UNION ALL
  SELECT "banana" as item
  UNION ALL
  SELECT "orange" as item)

SELECT
  SUBSTR(item, 2) as example
FROM items;

+---------+
| example |
+---------+
| pple    |
| anana   |
| range   |
+---------+
WITH items AS
  (SELECT "apple" as item
  UNION ALL
  SELECT "banana" as item
  UNION ALL
  SELECT "orange" as item)

SELECT
  SUBSTR(item, 2, 2) as example
FROM items;

+---------+
| example |
+---------+
| pp      |
| an      |
| ra      |
+---------+
WITH items AS
  (SELECT "apple" as item
  UNION ALL
  SELECT "banana" as item
  UNION ALL
  SELECT "orange" as item)

SELECT
  SUBSTR(item, -2) as example
FROM items;

+---------+
| example |
+---------+
| le      |
| na      |
| ge      |
+---------+

SUBSTRING

SUBSTRING(value, position[, length])

Alias for SUBSTR.

TO_BASE32

TO_BASE32(bytes_expr)

Description

Converts a sequence of BYTES into a base32-encoded STRING. To convert a base32-encoded STRING into BYTES, use FROM_BASE32.

Return type

STRING

Example

SELECT TO_BASE32(b'abcde\xFF') AS base32_string;

+------------------+
| base32_string    |
+------------------+
| MFRGGZDF74====== |
+------------------+

TO_BASE64

TO_BASE64(bytes_expr)

Description

Converts a sequence of BYTES into a base64-encoded STRING. To convert a base64-encoded STRING into BYTES, use FROM_BASE64.

Return type

STRING

Example

SELECT TO_BASE64(b'\xde\xad\xbe\xef') AS base64_string;

+---------------+
| base64_string |
+---------------+
| 3q2+7w==      |
+---------------+

TO_CODE_POINTS

TO_CODE_POINTS(value)

Description

Takes a value and returns an array of INT64.

  • If value is a STRING, each element in the returned array represents a code point. Each code point falls within the range of [0, 0xD7FF] and [0xE000, 0x10FFFF].
  • If value is BYTES, each element in the array is an extended ASCII character value in the range of [0, 255].

To convert from an array of code points to a STRING or BYTES, see CODE_POINTS_TO_STRING or CODE_POINTS_TO_BYTES.

Return type

ARRAY of INT64

Examples

The following example gets the code points for each element in an array of words.

SELECT word, TO_CODE_POINTS(word) AS code_points
FROM UNNEST(['foo', 'bar', 'baz', 'giraffe', 'llama']) AS word;

+---------+------------------------------------+
| word    | code_points                        |
+---------+------------------------------------+
| foo     | [102, 111, 111]                    |
| bar     | [98, 97, 114]                      |
| baz     | [98, 97, 122]                      |
| giraffe | [103, 105, 114, 97, 102, 102, 101] |
| llama   | [108, 108, 97, 109, 97]            |
+---------+------------------------------------+

The following example converts integer representations of BYTES to their corresponding ASCII character values.

SELECT word, TO_CODE_POINTS(word) AS bytes_value_as_integer
FROM UNNEST([b'\x00\x01\x10\xff', b'\x66\x6f\x6f']) AS word;

+------------------+------------------------+
| word             | bytes_value_as_integer |
+------------------+------------------------+
| \x00\x01\x10\xff | [0, 1, 16, 255]        |
| foo              | [102, 111, 111]        |
+------------------+------------------------+

The following example demonstrates the difference between a BYTES result and a STRING result.

SELECT TO_CODE_POINTS(b'Ā') AS b_result, TO_CODE_POINTS('Ā') AS s_result;

+------------+----------+
| b_result   | s_result |
+------------+----------+
| [196, 128] | [256]    |
+------------+----------+

Notice that the character, Ā, is represented as a two-byte Unicode sequence. As a result, the BYTES version of TO_CODE_POINTS returns an array with two elements, while the STRING version returns an array with a single element.

TO_HEX

TO_HEX(bytes)

Description

Converts a sequence of BYTES into a hexadecimal STRING. Converts each byte in the STRING as two hexadecimal characters in the range (0..9, a..f). To convert a hexadecimal-encoded STRING to BYTES, use FROM_HEX.

Return type

STRING

Example

WITH Input AS (
  SELECT b'\x00\x01\x02\x03\xAA\xEE\xEF\xFF' AS byte_str UNION ALL
  SELECT b'foobar'
)
SELECT byte_str, TO_HEX(byte_str) AS hex_str
FROM Input;

+----------------------------------+------------------+
| byte_string                      | hex_string       |
+----------------------------------+------------------+
| \x00\x01\x02\x03\xaa\xee\xef\xff | 00010203aaeeefff |
| foobar                           | 666f6f626172     |
+----------------------------------+------------------+

TRANSLATE

TRANSLATE(expression, source_characters, target_characters)

Description

In expression, replaces each character in source_characters with the corresponding character in target_characters. All inputs must be the same type, either STRING or BYTES.

  • Each character in expression is translated at most once.
  • A character in expression that is not present in source_characters is left unchanged in expression.
  • A character in source_characters without a corresponding character in target_characters is omitted from the result.
  • A duplicate character in source_characters results in an error.

Return type

STRING or BYTES

Examples

WITH example AS (
  SELECT 'This is a cookie' AS expression, 'sco' AS source_characters, 'zku' AS
  target_characters UNION ALL
  SELECT 'A coaster' AS expression, 'co' AS source_characters, 'k' as
  target_characters
)
SELECT expression, source_characters, target_characters, TRANSLATE(expression,
source_characters, target_characters) AS translate
FROM example;

+------------------+-------------------+-------------------+------------------+
| expression       | source_characters | target_characters | translate        |
+------------------+-------------------+-------------------+------------------+
| This is a cookie | sco               | zku               | Thiz iz a kuukie |
| A coaster        | co                | k                 | A kaster         |
+------------------+-------------------+-------------------+------------------+

TRIM

TRIM(value1[, value2])

Description

Removes all leading and trailing characters that match value2. If value2 is not specified, all leading and trailing whitespace characters (as defined by the Unicode standard) are removed. If the first argument is of type BYTES, the second argument is required.

If value2 contains more than one character or byte, the function removes all leading or trailing characters or bytes contained in value2.

Return type

STRING or BYTES

Examples

WITH items AS
  (SELECT "   apple   " as item
  UNION ALL
  SELECT "   banana   " as item
  UNION ALL
  SELECT "   orange   " as item)

SELECT
  CONCAT("#", TRIM(item), "#") as example
FROM items;

+----------+
| example  |
+----------+
| #apple#  |
| #banana# |
| #orange# |
+----------+
WITH items AS
  (SELECT "***apple***" as item
  UNION ALL
  SELECT "***banana***" as item
  UNION ALL
  SELECT "***orange***" as item)

SELECT
  TRIM(item, "*") as example
FROM items;

+---------+
| example |
+---------+
| apple   |
| banana  |
| orange  |
+---------+
WITH items AS
  (SELECT "xxxapplexxx" as item
  UNION ALL
  SELECT "yyybananayyy" as item
  UNION ALL
  SELECT "zzzorangezzz" as item
  UNION ALL
  SELECT "xyzpearxyz" as item)

SELECT
  TRIM(item, "xyz") as example
FROM items;

+---------+
| example |
+---------+
| apple   |
| banana  |
| orange  |
| pear    |
+---------+

UNICODE

UNICODE(value)

Description

Returns the Unicode code point for the first character in value. Returns 0 if value is empty, or if the resulting Unicode code point is 0.

Return type

INT64

Examples

SELECT UNICODE('âbcd') as A, UNICODE('â') as B, UNICODE('') as C, UNICODE(NULL) as D;

+-------+-------+-------+-------+
| A     | B     | C     | D     |
+-------+-------+-------+-------+
| 226   | 226   | 0     | NULL  |
+-------+-------+-------+-------+

UPPER

UPPER(value)

Description

For STRING arguments, returns the original string with all alphabetic characters in uppercase. Mapping between uppercase and lowercase is done according to the Unicode Character Database without taking into account language-specific mappings.

For BYTES arguments, the argument is treated as ASCII text, with all bytes greater than 127 left intact.

Return type

STRING or BYTES

Examples

WITH items AS
  (SELECT
    "foo" as item
  UNION ALL
  SELECT
    "bar" as item
  UNION ALL
  SELECT
    "baz" as item)

SELECT
  UPPER(item) AS example
FROM items;

+---------+
| example |
+---------+
| FOO     |
| BAR     |
| BAZ     |
+---------+

JSON functions

BigQuery supports functions that help you retrieve data stored in JSON-formatted strings and functions that help you transform data into JSON-formatted strings.

JSON_EXTRACT or JSON_EXTRACT_SCALAR

JSON_EXTRACT(json_string_expr, json_path_format), which returns JSON values as STRINGs.

JSON_EXTRACT_SCALAR(json_string_expr, json_path_format), which returns scalar JSON values as STRINGs.

Description

Extracts JSON values or JSON scalar values as strings.

  • json_string_expr: A JSON-formatted string. For example:

    {"class" : {"students" : [{"name" : "Jane"}]}}
    
  • json_path_format: The JSONpath format. This identifies the value or values you want to obtain from the JSON-formatted string. If json_path_format returns a JSON null, this is converted into a SQL NULL.

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets.

Return type

STRINGs

Examples

SELECT JSON_EXTRACT(json_text, '$') AS json_text_string
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------------------------------------------------+
| json_text_string                                          |
+-----------------------------------------------------------+
| {"class":{"students":[{"name":"Jane"}]}}                  |
| {"class":{"students":[]}}                                 |
| {"class":{"students":[{"name":"John"},{"name":"Jamie"}]}} |
+-----------------------------------------------------------+
SELECT JSON_EXTRACT(json_text, '$.class.students[0]') AS first_student
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------+
| first_student   |
+-----------------+
| {"name":"Jane"} |
| NULL            |
| {"name":"John"} |
+-----------------+
SELECT JSON_EXTRACT(json_text, '$.class.students[1].name') AS second_student_name
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name" : null}]}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-------------------+
| second_student    |
+-------------------+
| NULL              |
| NULL              |
| NULL              |
| "Jamie"           |
+-------------------+
SELECT JSON_EXTRACT(json_text, "$.class['students']") AS student_names
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+------------------------------------+
| student_names                      |
+------------------------------------+
| [{"name":"Jane"}]                  |
| []                                 |
| [{"name":"John"},{"name":"Jamie"}] |
+------------------------------------+
SELECT JSON_EXTRACT('{ "name" : "Jakob", "age" : "6" }', '$.name') as json_name,
  JSON_EXTRACT_SCALAR('{ "name" : "Jakob", "age" : "6" }', '$.name') as scalar_name,
  JSON_EXTRACT('{ "name" : "Jakob", "age" : "6" }', '$.age') as json_age,
  JSON_EXTRACT_SCALAR('{ "name" : "Jakob", "age" : "6" }', '$.age') as scalar;

+-----------+-------------+----------+--------+
| json_name | scalar_name | json_age | scalar |
+-----------+-------------+----------+--------+
| "Jakob"   | Jakob       | "6"      | 6      |
+-----------+-------------+----------+--------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets, [' ']. For example:

SELECT JSON_EXTRACT_SCALAR('{"a.b": {"c": "world"}}', "$['a.b'].c") as hello;

+-------+
| hello |
+-------+
| world |
+-------+

JSON_EXTRACT_ARRAY

JSON_EXTRACT_ARRAY(json_string_expr[, json_path_format])

Description

Extracts an array from a JSON-formatted string.

  • json_string_expr: A JSON-formatted string. For example:

    {"class" : {"students" : [{"name" : "Jane"}]}}
    
  • json_path_format: The JSONpath format. This identifies the value or values you want to obtain from the JSON-formatted string. If this optional parameter is not provided, the JSONPath $ symbol is applied, which means that the entire JSON-formatted string is analyzed.

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets.

Return type

ARRAY<STRING>

Examples

This extracts the items in a JSON-formatted string to a string array:

SELECT JSON_EXTRACT_ARRAY('[1,2,3]') as string_array

+----------------+
| string_array   |
+----------------+
| ['1','2','3']  |
+----------------+

This extracts a string array and converts it to an integer array:

SELECT ARRAY(
  SELECT CAST(integer_element as INT64)
  FROM UNNEST(
    JSON_EXTRACT_ARRAY('[1,2,3]','$')
  ) AS integer_element
) AS integer_array

+---------------+
| integer_array |
+---------------+
| [1,2,3]       |
+---------------+

This extracts string values in a JSON-formatted string to an array:

-- Don't strip the double quotes
SELECT JSON_EXTRACT_ARRAY('["apples","oranges","grapes"]', '$') as string_array

+--------------------------------------+
| string_array                         |
+--------------------------------------+
| ['"apples"','"oranges"','"grapes"']  |
+--------------------------------------+

-- Strip the double quotes
SELECT ARRAY(
  SELECT JSON_EXTRACT_SCALAR(string_element, '$')
  FROM UNNEST(JSON_EXTRACT_ARRAY('["apples","oranges","grapes"]','$')) AS string_element
) AS string_array

+---------------------------------+
|  string_array                   |
+---------------------------------+
| ['apples', 'oranges', 'grapes'] |
+---------------------------------+

This extracts only the items in fruit to an array:

SELECT JSON_EXTRACT_ARRAY(
  '{"fruit":[{"apples":5,"oranges":10},{"apples":2,"oranges":4}],"vegetables":[{"lettuce":7,"kale": 8}}',
  '$.fruit'
) as string_array

+----------------------------------------------------------------------+
| string_array                                                         |
+----------------------------------------------------------------------+
| ['{"apples" : 5, "oranges" : 10}' , '{"apples" : 2, "oranges" : 4}'] |
+----------------------------------------------------------------------+

These are equivalent:

JSON_EXTRACT_ARRAY('{"fruits":["apples","oranges","grapes"]}','$[fruits]') as string_array

JSON_EXTRACT_ARRAY('{"fruits":["apples","oranges","grapes"]}','$.fruits') as string_array

-- The queries above produce this result:
+---------------------------------------+
|  string_array                         |
+---------------------------------------+
| [""apples"", ""oranges"", ""grapes""] |
+---------------------------------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets, [' ']. For example:

SELECT JSON_EXTRACT_ARRAY('{"a.b": {"c": "world"}}', "$['a.b'].c") as hello;

+---------+
| hello   |
+---------+
| [world] |
+---------+

These examples explore how invalid requests and empty arrays are handled:

  • If a JSONPath is invalid, an error is thrown.
  • If a JSON-formatted string is invalid, the output is NULL.
  • It is okay to have empty arrays in the JSON-formatted string.
-- An error is thrown if you provide an invalid JSONPath.
JSON_EXTRACT_ARRAY('["foo","bar","baz"]','INVALID_JSONPath') as result

-- If a key is not specified when a key is expected, the result is NULL.
JSON_EXTRACT_ARRAY('{"a":"foo"}','$') as result

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a key that does not exist is specified, the result is NULL.
JSON_EXTRACT_ARRAY('{"a":"foo"}','$.b') as result

+--------+
| result |
+--------+
| NULL   |
+--------+

-- Empty arrays in JSON-formatted strings are supported.
JSON_EXTRACT_ARRAY('{"a":"foo","b":[]}','$.b') as result

+--------+
| result |
+--------+
| []     |
+--------+

JSON_QUERY or JSON_VALUE

JSON_QUERY(json_string_expr, json_path_format), which returns JSON values as STRINGs.

JSON_VALUE(json_string_expr, json_path_format), which returns scalar JSON values as STRINGs.

Description

Extracts JSON values or JSON scalar values as strings.

  • json_string_expr: A JSON-formatted string. For example:

    {"class" : {"students" : [{"name" : "Jane"}]}}
    
  • json_path_format: The JSONpath format. This identifies the value or values you want to obtain from the JSON-formatted string. If json_path_format returns a JSON null, this is converted into a SQL NULL.

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using double quotes.

Examples

SELECT JSON_QUERY(json_text, '$') AS json_text_string
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------------------------------------------------+
| json_text_string                                          |
+-----------------------------------------------------------+
| {"class":{"students":[{"name":"Jane"}]}}                  |
| {"class":{"students":[]}}                                 |
| {"class":{"students":[{"name":"John"},{"name":"Jamie"}]}} |
+-----------------------------------------------------------+
SELECT JSON_QUERY(json_text, '$.class.students[0]') AS first_student
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------+
| first_student   |
+-----------------+
| {"name":"Jane"} |
| NULL            |
| {"name":"John"} |
+-----------------+
SELECT JSON_QUERY(json_text, '$.class.students[1].name') AS second_student_name
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name" : null}]}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-------------------+
| second_student    |
+-------------------+
| NULL              |
| NULL              |
| NULL              |
| "Jamie"           |
+-------------------+
SELECT JSON_QUERY(json_text, '$.class."students"') AS student_names
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+------------------------------------+
| student_names                      |
+------------------------------------+
| [{"name":"Jane"}]                  |
| []                                 |
| [{"name":"John"},{"name":"Jamie"}] |
+------------------------------------+
SELECT JSON_QUERY('{ "name" : "Jakob", "age" : "6" }', '$.name') as json_name,
  JSON_VALUE('{ "name" : "Jakob", "age" : "6" }', '$.name') as scalar_name,
  JSON_QUERY('{ "name" : "Jakob", "age" : "6" }', '$.age') as json_age,
  JSON_VALUE('{ "name" : "Jakob", "age" : "6" }', '$.age') as scalar;

+-----------+-------------+----------+--------+
| json_name | scalar_name | json_age | scalar |
+-----------+-------------+----------+--------+
| "Jakob"   | Jakob       | "6"      | 6      |
+-----------+-------------+----------+--------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using double quotes. For example:

SELECT JSON_VALUE('{"a.b": {"c": "world"}}', '$."a.b".c') as hello;

+-------+
| hello |
+-------+
| world |
+-------+

TO_JSON_STRING

TO_JSON_STRING(value[, pretty_print])

Description

Returns a JSON-formatted string representation of value. This function supports an optional boolean parameter called pretty_print. If pretty_print is true, the returned value is formatted for easy readability.

Input data type Returned value
NULL of any type null
BOOL true or false.
INT64

Same as CAST(value AS STRING) when value is in the range of [-253, 253], which is the range of integers that can be represented losslessly as IEEE 754 double-precision floating point numbers. Values outside of this range are represented as quoted strings. For example:

-1
0
12345678901
9007199254740992
-9007199254740992
"9007199254740993"

9007199254740993 is greater than 253, so it is represented as a quoted string.

NUMERIC

Same as CAST(value AS STRING) when value is in the range of [-253, 253] and has no fractional part. Values outside of this range are represented as quoted strings. For example:

-1
0
"9007199254740993"
"123.56"
FLOAT64 +/-inf and NaN are represented as Infinity, -Infinity, and NaN, respectively.

Otherwise, the same as CAST(value AS STRING).

STRING Quoted string value, escaped according to the JSON standard. Specifically, ", \, and the control characters from U+0000 to U+001F are escaped.
BYTES

Quoted RFC 4648 base64-escaped value. For example:

"R29vZ2xl" is the base64 representation of bytes b"Google"

DATE

Quoted date. For example:

"2017-03-06"
TIMESTAMP

Quoted ISO 8601 date-time, where T separates the date and time and Zulu/UTC represents the time zone. For example:

"2017-03-06T12:34:56.789012Z"
DATETIME

Quoted ISO 8601 date-time, where T separates the date and time. For example:

"2017-03-06T12:34:56.789012"
TIME

Quoted ISO 8601 time. For example:

"12:34:56.789012"
ARRAY

Array of zero or more elements. Each element is formatted according to its type.

Example without formatting:

["red", "blue", "green"]

Example with formatting:

[
  "red",
  "blue",
  "green"
]
STRUCT

Object that contains zero or more key/value pairs. Each value is formatted according to its type.

Example without formatting:

{"colors":["red","blue"],"purchases":12,"inStock": true}

Example with formatting:

{
  "color":[
    "red",
    "blue"
   ]
  "purchases":12,
  "inStock": true
}

Fields with duplicate names might result in unparseable JSON. Anonymous fields are represented with "". If a field is a non-empty array or object, elements/fields are indented to the appropriate level.

Invalid UTF-8 field names might result in unparseable JSON. String values are escaped according to the JSON standard. Specifically, ", \, and the control characters from U+0000 to U+001F are escaped.

Return type

JSON string representation of the value.

Examples

Convert rows in a table to JSON.

With CoordinatesTable AS (
    (SELECT 1 AS id, [10,20] AS coordinates) UNION ALL
    (SELECT 2 AS id, [30,40] AS coordinates) UNION ALL
    (SELECT 3 AS id, [50,60] AS coordinates))
SELECT id, coordinates, TO_JSON_STRING(t) AS json_data
FROM CoordinatesTable as t;

+--------+-------------+--------------------------------+
| id     | coordinates | json_data                      |
+--------+-------------+--------------------------------+
| 1      | [10,20]     | {"id":1,"coordinates":[10,20]} |
| 2      | [30,40]     | {"id":2,"coordinates":[30,40]} |
| 3      | [50,60]     | {"id":3,"coordinates":[50,60]} |
+--------+-------------+--------------------------------+

Convert rows in a table to JSON with formatting.

With CoordinatesTable AS (
    (SELECT 1 AS id, [10,20] AS coordinates) UNION ALL
    (SELECT 2 AS id, [30,40] AS coordinates)
SELECT id, coordinates, TO_JSON_STRING(t, true) AS json_data
FROM CoordinatesTable as t;

+--------+-------------+---------------------+
| id     | coordinates | json_data           |
+--------+-------------+---------------------+
| 1      | [10,20]     | {                   |
|        |             |   "id":1,           |
|        |             |   "coordinates":[   |
|        |             |     10,             |
|        |             |     20              |
|        |             |   ]                 |
|        |             | }                   |
| 2      | [30,40]     | {                   |
|        |             |   "id":2,           |
|        |             |   "coordinates":[   |
|        |             |     30,             |
|        |             |     40              |
|        |             |   ]                 |
|        |             | }                   |
+--------+-------------+---------------------+

JSONPath format

Most JSON functions pass in a json_string_expr and json_path_format parameter. The json_string_expr parameter passes in a JSON-formatted string, and the json_path_format parameter identifies the value or values you want to obtain from the JSON-formatted string.

The json_string_expr parameter must be a JSON string that is formatted like this:

{"class" : {"students" : [{"name" : "Jane"}]}}

You construct the json_path_format parameter using the JSONPath format. As part of this format, this parameter must start with a $ symbol, which refers to the outermost level of the JSON-formatted string. You can identify child values using dots. If the JSON object is an array, you can use brackets to specify the array index. If the keys contain $, dots, or brackets, refer to each JSON function for how to escape them.

JSONPath Description Example Result using the above json_string_expr
$ Root object or element "$" {"class":{"students":[{"name":"Jane"}]}}
. Child operator "$.class.students" [{"name":"Jane"}]
[] Subscript operator "$.class.students[0]" {"name":"Jane"}

A JSON functions returns NULL if the json_path_format parameter does not match a value in json_string_expr. If the selected value for a scalar function is not scalar, such as an object or an array, the function returns NULL.

If the JSONPath is invalid, the function raises an error.

Array functions

ARRAY

ARRAY(subquery)

Description

The ARRAY function returns an ARRAY with one element for each row in a subquery.

If subquery produces a SQL table, the table must have exactly one column. Each element in the output ARRAY is the value of the single column of a row in the table.

If subquery produces a value table, then each element in the output ARRAY is the entire corresponding row of the value table.

Constraints

  • Subqueries are unordered, so the elements of the output ARRAY are not guaranteed to preserve any order in the source table for the subquery. However, if the subquery includes an ORDER BY clause, the ARRAY function will return an ARRAY that honors that clause.
  • If the subquery returns more than one column, the ARRAY function returns an error.
  • If the subquery returns an ARRAY typed column or ARRAY typed rows, the ARRAY function returns an error: BigQuery does not support ARRAYs with elements of type ARRAY.
  • If the subquery returns zero rows, the ARRAY function returns an empty ARRAY. It never returns a NULL ARRAY.

Return type

ARRAY

Examples

SELECT ARRAY
  (SELECT 1 UNION ALL
   SELECT 2 UNION ALL
   SELECT 3) AS new_array;

+-----------+
| new_array |
+-----------+
| [1, 2, 3] |
+-----------+

To construct an ARRAY from a subquery that contains multiple columns, change the subquery to use SELECT AS STRUCT. Now the ARRAY function will return an ARRAY of STRUCTs. The ARRAY will contain one STRUCT for each row in the subquery, and each of these STRUCTs will contain a field for each column in that row.

SELECT
  ARRAY
    (SELECT AS STRUCT 1, 2, 3
     UNION ALL SELECT AS STRUCT 4, 5, 6) AS new_array;

+------------------------+
| new_array              |
+------------------------+
| [{1, 2, 3}, {4, 5, 6}] |
+------------------------+

Similarly, to construct an ARRAY from a subquery that contains one or more ARRAYs, change the subquery to use SELECT AS STRUCT.

SELECT ARRAY
  (SELECT AS STRUCT [1, 2, 3] UNION ALL
   SELECT AS STRUCT [4, 5, 6]) AS new_array;

+----------------------------+
| new_array                  |
+----------------------------+
| [{[1, 2, 3]}, {[4, 5, 6]}] |
+----------------------------+

ARRAY_CONCAT

ARRAY_CONCAT(array_expression_1 [, array_expression_n])

Description

Concatenates one or more arrays with the same element type into a single array.

Return type

ARRAY

Examples

SELECT ARRAY_CONCAT([1, 2], [3, 4], [5, 6]) as count_to_six;

+--------------------------------------------------+
| count_to_six                                     |
+--------------------------------------------------+
| [1, 2, 3, 4, 5, 6]                               |
+--------------------------------------------------+

ARRAY_LENGTH

ARRAY_LENGTH(array_expression)

Description

Returns the size of the array. Returns 0 for an empty array. Returns NULL if the array_expression is NULL.

Return type

INT64

Examples

WITH items AS
  (SELECT ["coffee", NULL, "milk" ] as list
  UNION ALL
  SELECT ["cake", "pie"] as list)
SELECT ARRAY_TO_STRING(list, ', ', 'NULL'), ARRAY_LENGTH(list) AS size
FROM items
ORDER BY size DESC;

+---------------------------------+------+
| list                            | size |
+---------------------------------+------+
| [coffee, NULL, milk]            | 3    |
| [cake, pie]                     | 2    |
+---------------------------------+------+

ARRAY_TO_STRING

ARRAY_TO_STRING(array_expression, delimiter[, null_text])

Description

Returns a concatenation of the elements in array_expression as a STRING. The value for array_expression can either be an array of STRING or BYTES data types.

If the null_text parameter is used, the function replaces any NULL values in the array with the value of null_text.

If the null_text parameter is not used, the function omits the NULL value and its preceding delimiter.

Examples

WITH items AS
  (SELECT ["coffee", "tea", "milk" ] as list
  UNION ALL
  SELECT ["cake", "pie", NULL] as list)

SELECT ARRAY_TO_STRING(list, '--') AS text
FROM items;

+--------------------------------+
| text                           |
+--------------------------------+
| coffee--tea--milk              |
| cake--pie                      |
+--------------------------------+
WITH items AS
  (SELECT ["coffee", "tea", "milk" ] as list
  UNION ALL
  SELECT ["cake", "pie", NULL] as list)

SELECT ARRAY_TO_STRING(list, '--', 'MISSING') AS text
FROM items;

+--------------------------------+
| text                           |
+--------------------------------+
| coffee--tea--milk              |
| cake--pie--MISSING             |
+--------------------------------+

GENERATE_ARRAY

GENERATE_ARRAY(start_expression, end_expression[, step_expression])

Description

Returns an array of values. The start_expression and end_expression parameters determine the inclusive start and end of the array.

The GENERATE_ARRAY function accepts the following data types as inputs:

  • INT64
  • NUMERIC
  • FLOAT64

The step_expression parameter determines the increment used to generate array values. The default value for this parameter is 1.

This function returns an error if step_expression is set to 0, or if any input is NaN.

If any argument is NULL, the function will return a NULL array.

Return Data Type

ARRAY

Examples

The following returns an array of integers, with a default step of 1.

SELECT GENERATE_ARRAY(1, 5) AS example_array;

+-----------------+
| example_array   |
+-----------------+
| [1, 2, 3, 4, 5] |
+-----------------+

The following returns an array using a user-specified step size.

SELECT GENERATE_ARRAY(0, 10, 3) AS example_array;

+---------------+
| example_array |
+---------------+
| [0, 3, 6, 9]  |
+---------------+

The following returns an array using a negative value, -3 for its step size.

SELECT GENERATE_ARRAY(10, 0, -3) AS example_array;

+---------------+
| example_array |
+---------------+
| [10, 7, 4, 1] |
+---------------+

The following returns an array using the same value for the start_expression and end_expression.

SELECT GENERATE_ARRAY(4, 4, 10) AS example_array;

+---------------+
| example_array |
+---------------+
| [4]           |
+---------------+

The following returns an empty array, because the start_expression is greater than the end_expression, and the step_expression value is positive.

SELECT GENERATE_ARRAY(10, 0, 3) AS example_array;

+---------------+
| example_array |
+---------------+
| []            |
+---------------+

The following returns a NULL array because end_expression is NULL.

SELECT GENERATE_ARRAY(5, NULL, 1) AS example_array;

+---------------+
| example_array |
+---------------+
| NULL          |
+---------------+

The following returns multiple arrays.

SELECT GENERATE_ARRAY(start, 5) AS example_array
FROM UNNEST([3, 4, 5]) AS start;

+---------------+
| example_array |
+---------------+
| [3, 4, 5]     |
| [4, 5]        |
| [5]           |
+---------------+

GENERATE_DATE_ARRAY

GENERATE_DATE_ARRAY(start_date, end_date[, INTERVAL INT64_expr date_part])

Description

Returns an array of dates. The start_date and end_date parameters determine the inclusive start and end of the array.

The GENERATE_DATE_ARRAY function accepts the following data types as inputs:

  • start_date must be a DATE
  • end_date must be a DATE
  • INT64_expr must be an INT64
  • date_part must be either DAY, WEEK, MONTH, QUARTER, or YEAR.

The INT64_expr parameter determines the increment used to generate dates. The default value for this parameter is 1 day.

This function returns an error if INT64_expr is set to 0.

Return Data Type

An ARRAY containing 0 or more DATE values.

Examples

The following returns an array of dates, with a default step of 1.

SELECT GENERATE_DATE_ARRAY('2016-10-05', '2016-10-08') AS example;

+--------------------------------------------------+
| example                                          |
+--------------------------------------------------+
| [2016-10-05, 2016-10-06, 2016-10-07, 2016-10-08] |
+--------------------------------------------------+

The following returns an array using a user-specified step size.

SELECT GENERATE_DATE_ARRAY(
 '2016-10-05', '2016-10-09', INTERVAL 2 DAY) AS example;

+--------------------------------------+
| example                              |
+--------------------------------------+
| [2016-10-05, 2016-10-07, 2016-10-09] |
+--------------------------------------+

The following returns an array using a negative value, -3 for its step size.

SELECT GENERATE_DATE_ARRAY('2016-10-05',
  '2016-10-01', INTERVAL -3 DAY) AS example;

+--------------------------+
| example                  |
+--------------------------+
| [2016-10-05, 2016-10-02] |
+--------------------------+

The following returns an array using the same value for the start_dateand end_date.

SELECT GENERATE_DATE_ARRAY('2016-10-05',
  '2016-10-05', INTERVAL 8 DAY) AS example;

+--------------+
| example      |
+--------------+
| [2016-10-05] |
+--------------+

The following returns an empty array, because the start_date is greater than the end_date, and the step value is positive.

SELECT GENERATE_DATE_ARRAY('2016-10-05',
  '2016-10-01', INTERVAL 1 DAY) AS example;

+---------+
| example |
+---------+
| []      |
+---------+

The following returns a NULL array, because one of its inputs is NULL.

SELECT GENERATE_DATE_ARRAY('2016-10-05', NULL) AS example;

+---------+
| example |
+---------+
| NULL    |
+---------+

The following returns an array of dates, using MONTH as the date_part interval:

SELECT GENERATE_DATE_ARRAY('2016-01-01',
  '2016-12-31', INTERVAL 2 MONTH) AS example;

+--------------------------------------------------------------------------+
| example                                                                  |
+--------------------------------------------------------------------------+
| [2016-01-01, 2016-03-01, 2016-05-01, 2016-07-01, 2016-09-01, 2016-11-01] |
+--------------------------------------------------------------------------+

The following uses non-constant dates to generate an array.

SELECT GENERATE_DATE_ARRAY(date_start, date_end, INTERVAL 1 WEEK) AS date_range
FROM (
  SELECT DATE '2016-01-01' AS date_start, DATE '2016-01-31' AS date_end
  UNION ALL SELECT DATE "2016-04-01", DATE "2016-04-30"
  UNION ALL SELECT DATE "2016-07-01", DATE "2016-07-31"
  UNION ALL SELECT DATE "2016-10-01", DATE "2016-10-31"
) AS items;

+--------------------------------------------------------------+
| date_range                                                   |
+--------------------------------------------------------------+
| [2016-01-01, 2016-01-08, 2016-01-15, 2016-01-22, 2016-01-29] |
| [2016-04-01, 2016-04-08, 2016-04-15, 2016-04-22, 2016-04-29] |
| [2016-07-01, 2016-07-08, 2016-07-15, 2016-07-22, 2016-07-29] |
| [2016-10-01, 2016-10-08, 2016-10-15, 2016-10-22, 2016-10-29] |
+--------------------------------------------------------------+

GENERATE_TIMESTAMP_ARRAY

GENERATE_TIMESTAMP_ARRAY(start_timestamp, end_timestamp,
                         INTERVAL step_expression date_part)

Description

Returns an ARRAY of TIMESTAMPS separated by a given interval. The start_timestamp and end_timestamp parameters determine the inclusive lower and upper bounds of the ARRAY.

The GENERATE_TIMESTAMP_ARRAY function accepts the following data types as inputs:

  • start_timestamp: TIMESTAMP
  • end_timestamp: TIMESTAMP
  • step_expression: INT64
  • Allowed date_part values are: MICROSECOND, MILLISECOND, SECOND, MINUTE, HOUR, or DAY.

The step_expression parameter determines the increment used to generate timestamps.

Return Data Type

An ARRAY containing 0 or more TIMESTAMP values.

Examples

The following example returns an ARRAY of TIMESTAMPs at intervals of 1 day.

SELECT GENERATE_TIMESTAMP_ARRAY('2016-10-05 00:00:00', '2016-10-07 00:00:00',
                                INTERVAL 1 DAY) AS timestamp_array;

+--------------------------------------------------------------------------+
| timestamp_array                                                          |
+--------------------------------------------------------------------------+
| [2016-10-05 00:00:00+00, 2016-10-06 00:00:00+00, 2016-10-07 00:00:00+00] |
+--------------------------------------------------------------------------+

The following example returns an ARRAY of TIMESTAMPs at intervals of 1 second.

SELECT GENERATE_TIMESTAMP_ARRAY('2016-10-05 00:00:00', '2016-10-05 00:00:02',
                                INTERVAL 1 SECOND) AS timestamp_array;

+--------------------------------------------------------------------------+
| timestamp_array                                                          |
+--------------------------------------------------------------------------+
| [2016-10-05 00:00:00+00, 2016-10-05 00:00:01+00, 2016-10-05 00:00:02+00] |
+--------------------------------------------------------------------------+

The following example returns an ARRAY of TIMESTAMPS with a negative interval.

SELECT GENERATE_TIMESTAMP_ARRAY('2016-10-06 00:00:00', '2016-10-01 00:00:00',
                                INTERVAL -2 DAY) AS timestamp_array;

+--------------------------------------------------------------------------+
| timestamp_array                                                          |
+--------------------------------------------------------------------------+
| [2016-10-06 00:00:00+00, 2016-10-04 00:00:00+00, 2016-10-02 00:00:00+00] |
+--------------------------------------------------------------------------+

The following example returns an ARRAY with a single element, because start_timestamp and end_timestamp have the same value.

SELECT GENERATE_TIMESTAMP_ARRAY('2016-10-05 00:00:00', '2016-10-05 00:00:00',
                                INTERVAL 1 HOUR) AS timestamp_array;

+--------------------------+
| timestamp_array          |
+--------------------------+
| [2016-10-05 00:00:00+00] |
+--------------------------+

The following example returns an empty ARRAY, because start_timestamp is later than end_timestamp.

SELECT GENERATE_TIMESTAMP_ARRAY('2016-10-06 00:00:00', '2016-10-05 00:00:00',
                                INTERVAL 1 HOUR) AS timestamp_array;

+-----------------+
| timestamp_array |
+-----------------+
| []              |
+-----------------+

The following example returns a null ARRAY, because one of the inputs is NULL.

SELECT GENERATE_TIMESTAMP_ARRAY('2016-10-05 00:00:00', NULL, INTERVAL 1 HOUR)
  AS timestamp_array;

+-----------------+
| timestamp_array |
+-----------------+
| NULL            |
+-----------------+

The following example generates ARRAYs of TIMESTAMPs from columns containing values for start_timestamp and end_timestamp.

SELECT GENERATE_TIMESTAMP_ARRAY(start_timestamp, end_timestamp, INTERVAL 1 HOUR)
  AS timestamp_array
FROM
  (SELECT
    TIMESTAMP '2016-10-05 00:00:00' AS start_timestamp,
    TIMESTAMP '2016-10-05 02:00:00' AS end_timestamp
   UNION ALL
   SELECT
    TIMESTAMP '2016-10-05 12:00:00' AS start_timestamp,
    TIMESTAMP '2016-10-05 14:00:00' AS end_timestamp
   UNION ALL
   SELECT
    TIMESTAMP '2016-10-05 23:59:00' AS start_timestamp,
    TIMESTAMP '2016-10-06 01:59:00' AS end_timestamp);

+--------------------------------------------------------------------------+
| timestamp_array                                                          |
+--------------------------------------------------------------------------+
| [2016-10-05 00:00:00+00, 2016-10-05 01:00:00+00, 2016-10-05 02:00:00+00] |
| [2016-10-05 12:00:00+00, 2016-10-05 13:00:00+00, 2016-10-05 14:00:00+00] |
| [2016-10-05 23:59:00+00, 2016-10-06 00:59:00+00, 2016-10-06 01:59:00+00] |
+--------------------------------------------------------------------------+

OFFSET and ORDINAL

array_expression[OFFSET(zero_based_offset)]
array_expression[ORDINAL(one_based_offset)]

Description

Accesses an ARRAY element by position and returns the element. OFFSET means that the numbering starts at zero, ORDINAL means that the numbering starts at one.

A given array can be interpreted as either 0-based or 1-based. When accessing an array element, you must preface the array position with OFFSET or ORDINAL, respectively; there is no default behavior.

Both OFFSET and ORDINAL generate an error if the index is out of range.

Return type

Varies depending on the elements in the ARRAY.

Examples

WITH items AS
  (SELECT ["apples", "bananas", "pears", "grapes"] as list
  UNION ALL
  SELECT ["coffee", "tea", "milk" ] as list
  UNION ALL
  SELECT ["cake", "pie"] as list)

SELECT list, list[OFFSET(1)] as offset_1, list[ORDINAL(1)] as ordinal_1
FROM items;

+----------------------------------+-----------+-----------+
| list                             | offset_1  | ordinal_1 |
+----------------------------------+-----------+-----------+
| [apples, bananas, pears, grapes] | bananas   | apples    |
| [coffee, tea, milk]              | tea       | coffee    |
| [cake, pie]                      | pie       | cake      |
+----------------------------------+-----------+-----------+

ARRAY_REVERSE

ARRAY_REVERSE(value)

Description

Returns the input ARRAY with elements in reverse order.

Return type

ARRAY

Examples

WITH example AS (
  SELECT [1, 2, 3] AS arr UNION ALL
  SELECT [4, 5] AS arr UNION ALL
  SELECT [] AS arr
)
SELECT
  arr,
  ARRAY_REVERSE(arr) AS reverse_arr
FROM example;

+-----------+-------------+
| arr       | reverse_arr |
+-----------+-------------+
| [1, 2, 3] | [3, 2, 1]   |
| [4, 5]    | [5, 4]      |
| []        | []          |
+-----------+-------------+

SAFE_OFFSET and SAFE_ORDINAL

array_expression[SAFE_OFFSET(zero_based_offset)]
array_expression[SAFE_ORDINAL(one_based_offset)]

Description

Identical to OFFSET and ORDINAL, except returns NULL if the index is out of range.

Return type

Varies depending on the elements in the ARRAY.

Example

WITH items AS
  (SELECT ["apples", "bananas", "pears", "grapes"] as list
  UNION ALL
  SELECT ["coffee", "tea", "milk" ] as list
  UNION ALL
  SELECT ["cake", "pie"] as list)

SELECT list,
  list[SAFE_OFFSET(3)] as safe_offset_3,
  list[SAFE_ORDINAL(3)] as safe_ordinal_3
FROM items;

+----------------------------------+---------------+----------------+
| list                             | safe_offset_3 | safe_ordinal_3 |
+----------------------------------+---------------+----------------+
| [apples, bananas, pears, grapes] | grapes        | pears          |
| [coffee, tea, milk]              | NULL          | milk           |
| [cake, pie]                      | NULL          | NULL           |
+----------------------------------+---------------+----------------+

Date functions

BigQuery supports the following DATE functions.

CURRENT_DATE

CURRENT_DATE([time_zone])

Description

Returns the current date as of the specified or default timezone.

This function supports an optional time_zone parameter. This parameter is a string representing the timezone to use. If no timezone is specified, the default timezone, UTC, is used. See Timezone definitions for information on how to specify a time zone.

If the time_zone parameter evaluates to NULL, this function returns NULL.

Return Data Type

DATE

Example

SELECT CURRENT_DATE() as the_date;

+--------------+
| the_date     |
+--------------+
| 2016-12-25   |
+--------------+

EXTRACT

EXTRACT(part FROM date_expression)

Description

Returns the value corresponding to the specified date part. The part must be one of:

  • DAYOFWEEK: Returns values in the range [1,7] with Sunday as the first day of the week.
  • DAY
  • DAYOFYEAR
  • WEEK: Returns the week number of the date in the range [0, 53]. Weeks begin with Sunday, and dates prior to the first Sunday of the year are in week 0.
  • WEEK(<WEEKDAY>): Returns the week number of the date in the range [0, 53]. Weeks begin on WEEKDAY. Dates prior to the first WEEKDAY of the year are in week 0. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK: Returns the ISO 8601 week number of the date_expression. ISOWEEKs begin on Monday. Return values are in the range [1, 53]. The first ISOWEEK of each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year.
  • MONTH
  • QUARTER: Returns values in the range [1,4].
  • YEAR
  • ISOYEAR: Returns the ISO 8601 week-numbering year, which is the Gregorian calendar year containing the Thursday of the week to which date_expression belongs.

Return Data Type

INT64

Examples

In the following example, EXTRACT returns a value corresponding to the DAY date part.

SELECT EXTRACT(DAY FROM DATE '2013-12-25') as the_day;

+---------+
| the_day |
+---------+
| 25      |
+---------+

In the following example, EXTRACT returns values corresponding to different date parts from a column of dates near the end of the year.

SELECT
  date,
  EXTRACT(ISOYEAR FROM date) AS isoyear,
  EXTRACT(ISOWEEK FROM date) AS isoweek,
  EXTRACT(YEAR FROM date) AS year,
  EXTRACT(WEEK FROM date) AS week
FROM UNNEST(GENERATE_DATE_ARRAY('2015-12-23', '2016-01-09')) AS date
ORDER BY date;
+------------+---------+---------+------+------+
| date       | isoyear | isoweek | year | week |
+------------+---------+---------+------+------+
| 2015-12-23 | 2015    | 52      | 2015 | 51   |
| 2015-12-24 | 2015    | 52      | 2015 | 51   |
| 2015-12-25 | 2015    | 52      | 2015 | 51   |
| 2015-12-26 | 2015    | 52      | 2015 | 51   |
| 2015-12-27 | 2015    | 52      | 2015 | 52   |
| 2015-12-28 | 2015    | 53      | 2015 | 52   |
| 2015-12-29 | 2015    | 53      | 2015 | 52   |
| 2015-12-30 | 2015    | 53      | 2015 | 52   |
| 2015-12-31 | 2015    | 53      | 2015 | 52   |
| 2016-01-01 | 2015    | 53      | 2016 | 0    |
| 2016-01-02 | 2015    | 53      | 2016 | 0    |
| 2016-01-03 | 2015    | 53      | 2016 | 1    |
| 2016-01-04 | 2016    | 1       | 2016 | 1    |
| 2016-01-05 | 2016    | 1       | 2016 | 1    |
| 2016-01-06 | 2016    | 1       | 2016 | 1    |
| 2016-01-07 | 2016    | 1       | 2016 | 1    |
| 2016-01-08 | 2016    | 1       | 2016 | 1    |
| 2016-01-09 | 2016    | 1       | 2016 | 1    |
+------------+---------+---------+------+------+

In the following example, date_expression falls on a Sunday. EXTRACT calculates the first column using weeks that begin on Sunday, and it calculates the second column using weeks that begin on Monday.

WITH table AS (SELECT DATE('2017-11-05') AS date)
SELECT
  date,
  EXTRACT(WEEK(SUNDAY) FROM date) AS week_sunday,
  EXTRACT(WEEK(MONDAY) FROM date) AS week_monday FROM table;

+------------+-------------+-------------+
| date       | week_sunday | week_monday |
+------------+-------------+-------------+
| 2017-11-05 | 45          | 44          |
+------------+-------------+-------------+

DATE

1. DATE(year, month, day)
2. DATE(timestamp_expression[, timezone])
3. DATE(datetime_expression)

Description

  1. Constructs a DATE from INT64 values representing the year, month, and day.
  2. Extracts the DATE from a TIMESTAMP expression. It supports an optional parameter to specify a timezone. If no timezone is specified, the default timezone, UTC, is used.
  3. Extracts the DATE from a DATETIME expression.

Return Data Type

DATE

Example

SELECT
  DATE(2016, 12, 25) as date_ymd,
  DATE(DATETIME "2016-12-25 23:59:59") as date_dt,
  DATE(TIMESTAMP "2016-12-25 05:30:00+07", "America/Los_Angeles") as date_tstz;

+------------+------------+------------+
| date_ymd   | date_dt    | date_tstz  |
+------------+------------+------------+
| 2016-12-25 | 2016-12-25 | 2016-12-24 |
+------------+------------+------------+

DATE_ADD

DATE_ADD(date_expression, INTERVAL int64_expression date_part)

Description

Adds a specified time interval to a DATE.

DATE_ADD supports the following date_part values:

  • DAY
  • WEEK. Equivalent to 7 DAYs.
  • MONTH
  • QUARTER
  • YEAR

Special handling is required for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original date's day, then the result day is the last day of the new month.

Return Data Type

DATE

Example

SELECT DATE_ADD(DATE "2008-12-25", INTERVAL 5 DAY) as five_days_later;

+--------------------+
| five_days_later    |
+--------------------+
| 2008-12-30         |
+--------------------+

DATE_SUB

DATE_SUB(date_expression, INTERVAL int64_expression date_part)

Description

Subtracts a specified time interval from a DATE.

DATE_SUB supports the following date_part values:

  • DAY
  • WEEK. Equivalent to 7 DAYs.
  • MONTH
  • QUARTER
  • YEAR

Special handling is required for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original date's day, then the result day is the last day of the new month.

Return Data Type

DATE

Example

SELECT DATE_SUB(DATE "2008-12-25", INTERVAL 5 DAY) as five_days_ago;

+---------------+
| five_days_ago |
+---------------+
| 2008-12-20    |
+---------------+

DATE_DIFF

DATE_DIFF(date_expression_a, date_expression_b, date_part)

Description

Returns the number of whole specified date_part intervals between two DATE objects (date_expression_a - date_expression_b). If the first DATE is earlier than the second one, the output is negative.

DATE_DIFF supports the following date_part values:

  • DAY
  • WEEK This date part begins on Sunday.
  • WEEK(<WEEKDAY>): This date part begins on WEEKDAY. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK: Uses ISO 8601 week boundaries. ISO weeks begin on Monday.
  • MONTH
  • QUARTER
  • YEAR
  • ISOYEAR: Uses the ISO 8601 week-numbering year boundary. The ISO year boundary is the Monday of the first week whose Thursday belongs to the corresponding Gregorian calendar year.

Return Data Type

INT64

Example

SELECT DATE_DIFF(DATE '2010-07-07', DATE '2008-12-25', DAY) as days_diff;

+-----------+
| days_diff |
+-----------+
| 559       |
+-----------+
SELECT
  DATE_DIFF(DATE '2017-10-15', DATE '2017-10-14', DAY) as days_diff,
  DATE_DIFF(DATE '2017-10-15', DATE '2017-10-14', WEEK) as weeks_diff;

+-----------+------------+
| days_diff | weeks_diff |
+-----------+------------+
| 1         | 1          |
+-----------+------------+

The example above shows the result of DATE_DIFF for two days in succession. DATE_DIFF with the date part WEEK returns 1 because DATE_DIFF counts the number of date part boundaries in this range of dates. Each WEEK begins on Sunday, so there is one date part boundary between Saturday, 2017-10-14 and Sunday, 2017-10-15.

The following example shows the result of DATE_DIFF for two dates in different years. DATE_DIFF with the date part YEAR returns 3 because it counts the number of Gregorian calendar year boundaries between the two dates. DATE_DIFF with the date part ISOYEAR returns 2 because the second date belongs to the ISO year 2015. The first Thursday of the 2015 calendar year was 2015-01-01, so the ISO year 2015 begins on the preceding Monday, 2014-12-29.

SELECT
  DATE_DIFF('2017-12-30', '2014-12-30', YEAR) AS year_diff,
  DATE_DIFF('2017-12-30', '2014-12-30', ISOYEAR) AS isoyear_diff;

+-----------+--------------+
| year_diff | isoyear_diff |
+-----------+--------------+
| 3         | 2            |
+-----------+--------------+

The following example shows the result of DATE_DIFF for two days in succession. The first date falls on a Monday and the second date falls on a Sunday. DATE_DIFF with the date part WEEK returns 0 because this date part uses weeks that begin on Sunday. DATE_DIFF with the date part WEEK(MONDAY) returns 1. DATE_DIFF with the date part ISOWEEK also returns 1 because ISO weeks begin on Monday.

SELECT
  DATE_DIFF('2017-12-18', '2017-12-17', WEEK) AS week_diff,
  DATE_DIFF('2017-12-18', '2017-12-17', WEEK(MONDAY)) AS week_weekday_diff,
  DATE_DIFF('2017-12-18', '2017-12-17', ISOWEEK) AS isoweek_diff;

+-----------+-------------------+--------------+
| week_diff | week_weekday_diff | isoweek_diff |
+-----------+-------------------+--------------+
| 0         | 1                 | 1            |
+-----------+-------------------+--------------+

DATE_TRUNC

DATE_TRUNC(date_expression, date_part)

Description

Truncates the date to the specified granularity.

DATE_TRUNC supports the following values for date_part:

  • DAY
  • WEEK
  • WEEK(<WEEKDAY>): Truncates date_expression to the preceding week boundary, where weeks begin on WEEKDAY. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK: Truncates date_expression to the preceding ISO 8601 week boundary. ISOWEEKs begin on Monday. The first ISOWEEK of each ISO year contains the first Thursday of the corresponding Gregorian calendar year. Any date_expression earlier than this will truncate to the preceding Monday.
  • MONTH
  • QUARTER
  • YEAR
  • ISOYEAR: Truncates date_expression to the preceding ISO 8601 week-numbering year boundary. The ISO year boundary is the Monday of the first week whose Thursday belongs to the corresponding Gregorian calendar year.

Return Data Type

DATE

Examples

SELECT DATE_TRUNC(DATE '2008-12-25', MONTH) as month;

+------------+
| month      |
+------------+
| 2008-12-01 |
+------------+

In the following example, the original date falls on a Sunday. Because the date_part is WEEK(MONDAY), DATE_TRUNC returns the DATE for the preceding Monday.

SELECT date AS original, DATE_TRUNC(date, WEEK(MONDAY)) AS truncated
FROM (SELECT DATE('2017-11-05') AS date);

+------------+------------+
| original   | truncated  |
+------------+------------+
| 2017-11-05 | 2017-10-30 |
+------------+------------+

In the following example, the original date_expression is in the Gregorian calendar year 2015. However, DATE_TRUNC with the ISOYEAR date part truncates the date_expression to the beginning of the ISO year, not the Gregorian calendar year. The first Thursday of the 2015 calendar year was 2015-01-01, so the ISO year 2015 begins on the preceding Monday, 2014-12-29. Therefore the ISO year boundary preceding the date_expression 2015-06-15 is 2014-12-29.

SELECT
  DATE_TRUNC('2015-06-15', ISOYEAR) AS isoyear_boundary,
  EXTRACT(ISOYEAR FROM DATE '2015-06-15') AS isoyear_number;

+------------------+----------------+
| isoyear_boundary | isoyear_number |
+------------------+----------------+
| 2014-12-29       | 2015           |
+------------------+----------------+

DATE_FROM_UNIX_DATE

DATE_FROM_UNIX_DATE(int64_expression)

Description

Interprets int64_expression as the number of days since 1970-01-01.

Return Data Type

DATE

Example

SELECT DATE_FROM_UNIX_DATE(14238) as date_from_epoch;

+-----------------+
| date_from_epoch |
+-----------------+
| 2008-12-25      |
+-----------------+

FORMAT_DATE

FORMAT_DATE(format_string, date_expr)

Description

Formats the date_expr according to the specified format_string.

See Supported Format Elements For DATE for a list of format elements that this function supports.

Return Data Type

STRING

Examples

SELECT FORMAT_DATE("%x", DATE "2008-12-25") as US_format;

+------------+
| US_format  |
+------------+
| 12/25/08   |
+------------+
SELECT FORMAT_DATE("%b-%d-%Y", DATE "2008-12-25") AS formatted;

+-------------+
| formatted   |
+-------------+
| Dec-25-2008 |
+-------------+
SELECT FORMAT_DATE("%b %Y", DATE "2008-12-25") AS formatted;

+-------------+
| formatted   |
+-------------+
| Dec 2008    |
+-------------+

LAST_DAY

LAST_DAY(date_expression[, date_part])

Description

Returns the last day from a date expression. This is commonly used to return the last day of the month.

You can optionally specify the date part for which the last day is returned. If this parameter is not used, the default value is MONTH. LAST_DAY supports the following values for date_part:

  • YEAR
  • QUARTER
  • MONTH
  • WEEK. Equivalent to 7 DAYs.
  • WEEK(<WEEKDAY>). <WEEKDAY> represents the starting day of the week. Valid values are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK. Uses ISO 8601 week boundaries. ISO weeks begin on Monday.
  • ISOYEAR. Uses the ISO 8601 week-numbering year boundary. The ISO year boundary is the Monday of the first week whose Thursday belongs to the corresponding Gregorian calendar year.

Return Data Type

DATE

Example

These both return the last day of the month:

SELECT LAST_DAY(DATE '2008-11-25', MONTH) AS last_day

+------------+
| last_day   |
+------------+
| 2008-11-30 |
+------------+
SELECT LAST_DAY(DATE '2008-11-25') AS last_day

+------------+
| last_day   |
+------------+
| 2008-11-30 |
+------------+

This returns the last day of the year:

SELECT LAST_DAY(DATE '2008-11-25', YEAR) AS last_day

+------------+
| last_day   |
+------------+
| 2008-12-31 |
+------------+

This returns the last day of the week for a week that starts on a Sunday:

SELECT LAST_DAY(DATE '2008-11-10', WEEK(SUNDAY)) AS last_day

+------------+
| last_day   |
+------------+
| 2008-11-15 |
+------------+

This returns the last day of the week for a week that starts on a Monday:

SELECT LAST_DAY(DATE '2008-11-10', WEEK(MONDAY)) AS last_day

+------------+
| last_day   |
+------------+
| 2008-11-16 |
+------------+

PARSE_DATE

PARSE_DATE(format_string, date_string)

Description

Converts a string representation of date to a DATE object.

format_string contains the format elements that define how date_string is formatted. Each element in date_string must have a corresponding element in format_string. The location of each element in format_string must match the location of each element in date_string.

-- This works because elements on both sides match.
SELECT PARSE_DATE("%A %b %e %Y", "Thursday Dec 25 2008")

-- This doesn't work because the year element is in different locations.
SELECT PARSE_DATE("%Y %A %b %e", "Thursday Dec 25 2008")

-- This doesn't work because one of the year elements is missing.
SELECT PARSE_DATE("%A %b %e", "Thursday Dec 25 2008")

-- This works because %F can find all matching elements in date_string.
SELECT PARSE_DATE("%F", "2000-12-30")

The format string fully supports most format elements except for %Q, %a, %A, %g, %G, %j, %u, %U, %V, %w, and %W.

When using PARSE_DATE, keep the following in mind:

  • Unspecified fields. Any unspecified field is initialized from 1970-01-01.
  • Case insensitive names. Names, such as Monday, February, and so on, are case insensitive.
  • Whitespace. One or more consecutive white spaces in the format string matches zero or more consecutive white spaces in the date string. In addition, leading and trailing white spaces in the date string are always allowed -- even if they are not in the format string.
  • Format precedence. When two (or more) format elements have overlapping information (for example both %F and %Y affect the year), the last one generally overrides any earlier ones.

Return Data Type

DATE

Examples

This example converts a MM/DD/YY formatted string to a DATE object:

SELECT PARSE_DATE("%x", "12/25/08") as parsed;

+------------+
| parsed     |
+------------+
| 2008-12-25 |
+------------+

This example converts a YYYYMMDD formatted string to a DATE object:

SELECT PARSE_DATE("%Y%m%d", "20081225") as parsed;

+------------+
| parsed     |
+------------+
| 2008-12-25 |
+------------+

UNIX_DATE

UNIX_DATE(date_expression)

Description

Returns the number of days since 1970-01-01.

Return Data Type

INT64

Example

SELECT UNIX_DATE(DATE "2008-12-25") as days_from_epoch;

+-----------------+
| days_from_epoch |
+-----------------+
| 14238           |
+-----------------+

Supported format elements for DATE

Unless otherwise noted, DATE functions that use format strings support the following elements:

Format element Description
%A The full weekday name.
%a The abbreviated weekday name.
%B The full month name.
%b or %h The abbreviated month name.
%C The century (a year divided by 100 and truncated to an integer) as a decimal number (00-99).
%D The date in the format %m/%d/%y.
%d The day of the month as a decimal number (01-31).
%e The day of month as a decimal number (1-31); single digits are preceded by a space.
%F The date in the format %Y-%m-%d.
%G The ISO 8601 year with century as a decimal number. Each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year. Note that %G and %Y may produce different results near Gregorian year boundaries, where the Gregorian year and ISO year can diverge.
%g The ISO 8601 year without century as a decimal number (00-99). Each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year. Note that %g and %y may produce different results near Gregorian year boundaries, where the Gregorian year and ISO year can diverge.
%j The day of the year as a decimal number (001-366).
%m The month as a decimal number (01-12).
%n A newline character.
%Q The quarter as a decimal number (1-4).
%t A tab character.
%U The week number of the year (Sunday as the first day of the week) as a decimal number (00-53).
%u The weekday (Monday as the first day of the week) as a decimal number (1-7).
%V The ISO 8601 week number of the year (Monday as the first day of the week) as a decimal number (01-53). If the week containing January 1 has four or more days in the new year, then it is week 1; otherwise it is week 53 of the previous year, and the next week is week 1.
%W The week number of the year (Monday as the first day of the week) as a decimal number (00-53).
%w The weekday (Sunday as the first day of the week) as a decimal number (0-6).
%x The date representation in MM/DD/YY format.
%Y The year with century as a decimal number.
%y The year without century as a decimal number (00-99), with an optional leading zero. Can be mixed with %C. If %C is not specified, years 00-68 are 2000s, while years 69-99 are 1900s.
%E4Y Four-character years (0001 ... 9999). Note that %Y produces as many characters as it takes to fully render the year.

Datetime functions

BigQuery supports the following DATETIME functions.

All outputs are automatically formatted as per ISO 8601, separating date and time with aT.

CURRENT_DATETIME

CURRENT_DATETIME([timezone])

Description

Returns the current time as a DATETIME object.

This function supports an optional timezone parameter. See Timezone definitions for information on how to specify a time zone.

Return Data Type

DATETIME

Example

SELECT CURRENT_DATETIME() as now;

+----------------------------+
| now                        |
+----------------------------+
| 2016-05-19T10:38:47.046465 |
+----------------------------+

DATETIME

1. DATETIME(year, month, day, hour, minute, second)
2. DATETIME(date_expression[, time_expression])
3. DATETIME(timestamp_expression [, timezone])

Description

  1. Constructs a DATETIME object using INT64 values representing the year, month, day, hour, minute, and second.
  2. Constructs a DATETIME object using a DATE object and an optional TIME object.
  3. Constructs a DATETIME object using a TIMESTAMP object. It supports an optional parameter to specify a timezone. If no timezone is specified, the default timezone, UTC, is used.

Return Data Type

DATETIME

Example

SELECT
  DATETIME(2008, 12, 25, 05, 30, 00) as datetime_ymdhms,
  DATETIME(TIMESTAMP "2008-12-25 05:30:00+00", "America/Los_Angeles") as datetime_tstz;

+---------------------+---------------------+
| datetime_ymdhms     | datetime_tstz       |
+---------------------+---------------------+
| 2008-12-25T05:30:00 | 2008-12-24T21:30:00 |
+---------------------+---------------------+

EXTRACT

EXTRACT(part FROM datetime_expression)

Description

Returns a value that corresponds to the specified part from a supplied datetime_expression.

Allowed part values are:

  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAYOFWEEK
  • DAY
  • DAYOFYEAR
  • WEEK: Returns the week number of the date in the range [0, 53]. Weeks begin with Sunday, and dates prior to the first Sunday of the year are in week 0.
  • WEEK(<WEEKDAY>): Returns the week number of datetime_expression in the range [0, 53]. Weeks begin on WEEKDAY. datetimes prior to the first WEEKDAY of the year are in week 0. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK: Returns the ISO 8601 week number of the datetime_expression. ISOWEEKs begin on Monday. Return values are in the range [1, 53]. The first ISOWEEK of each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year.
  • MONTH
  • QUARTER
  • YEAR
  • ISOYEAR: Returns the ISO 8601 week-numbering year, which is the Gregorian calendar year containing the Thursday of the week to which date_expression belongs.
  • DATE
  • TIME

Returned values truncate lower order time periods. For example, when extracting seconds, EXTRACT truncates the millisecond and microsecond values.

Return Data Type

INT64, except in the following cases:

  • If part is DATE, returns a DATE object.
  • If part is TIME, returns a TIME object.

Examples

In the following example, EXTRACT returns a value corresponding to the HOUR time part.

SELECT EXTRACT(HOUR FROM DATETIME(2008, 12, 25, 15, 30, 00)) as hour;

+------------------+
| hour             |
+------------------+
| 15               |
+------------------+

In the following example, EXTRACT returns values corresponding to different time parts from a column of datetimes.

WITH Datetimes AS (
  SELECT DATETIME '2005-01-03 12:34:56' AS datetime UNION ALL
  SELECT DATETIME '2007-12-31' UNION ALL
  SELECT DATETIME '2009-01-01' UNION ALL
  SELECT DATETIME '2009-12-31' UNION ALL
  SELECT DATETIME '2017-01-02' UNION ALL
  SELECT DATETIME '2017-05-26'
)
SELECT
  datetime,
  EXTRACT(ISOYEAR FROM datetime) AS isoyear,
  EXTRACT(ISOWEEK FROM datetime) AS isoweek,
  EXTRACT(YEAR FROM datetime) AS year,
  EXTRACT(WEEK FROM datetime) AS week
FROM Datetimes
ORDER BY datetime;

+---------------------+---------+---------+------+------+
| datetime            | isoyear | isoweek | year | week |
+---------------------+---------+---------+------+------+
| 2005-01-03T12:34:56 | 2005    | 1       | 2005 | 1    |
| 2007-12-31T00:00:00 | 2008    | 1       | 2007 | 52   |
| 2009-01-01T00:00:00 | 2009    | 1       | 2009 | 0    |
| 2009-12-31T00:00:00 | 2009    | 53      | 2009 | 52   |
| 2017-01-02T00:00:00 | 2017    | 1       | 2017 | 1    |
| 2017-05-26T00:00:00 | 2017    | 21      | 2017 | 21   |
+---------------------+---------+---------+------+------+

In the following example, datetime_expression falls on a Sunday. EXTRACT calculates the first column using weeks that begin on Sunday, and it calculates the second column using weeks that begin on Monday.

WITH table AS (SELECT DATETIME(TIMESTAMP "2017-11-05 00:00:00+00", "UTC") AS datetime)
SELECT
  datetime,
  EXTRACT(WEEK(SUNDAY) FROM datetime) AS week_sunday,
  EXTRACT(WEEK(MONDAY) FROM datetime) AS week_monday
FROM table;

+---------------------+-------------+---------------+
| datetime            | week_sunday | week_monday   |
+---------------------+-------------+---------------+
| 2017-11-05T00:00:00 | 45          | 44            |
+---------------------+-------------+---------------+

DATETIME_ADD

DATETIME_ADD(datetime_expression, INTERVAL int64_expression part)

Description

Adds int64_expression units of part to the DATETIME object.

DATETIME_ADD supports the following values for part:

  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAY
  • WEEK. Equivalent to 7 DAYs.
  • MONTH
  • QUARTER
  • YEAR

Special handling is required for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original DATETIME's day, then the result day is the last day of the new month.

Return Data Type

DATETIME

Example

SELECT
  DATETIME "2008-12-25 15:30:00" as original_date,
  DATETIME_ADD(DATETIME "2008-12-25 15:30:00", INTERVAL 10 MINUTE) as later;

+-----------------------------+------------------------+
| original_date               | later                  |
+-----------------------------+------------------------+
| 2008-12-25T15:30:00         | 2008-12-25T15:40:00    |
+-----------------------------+------------------------+

DATETIME_SUB

DATETIME_SUB(datetime_expression, INTERVAL int64_expression part)

Description

Subtracts int64_expression units of part from the DATETIME.

DATETIME_SUB supports the following values for part:

  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAY
  • WEEK. Equivalent to 7 DAYs.
  • MONTH
  • QUARTER
  • YEAR

Special handling is required for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original DATETIME's day, then the result day is the last day of the new month.

Return Data Type

DATETIME

Example

SELECT
  DATETIME "2008-12-25 15:30:00" as original_date,
  DATETIME_SUB(DATETIME "2008-12-25 15:30:00", INTERVAL 10 MINUTE) as earlier;

+-----------------------------+------------------------+
| original_date               | earlier                |
+-----------------------------+------------------------+
| 2008-12-25T15:30:00         | 2008-12-25T15:20:00    |
+-----------------------------+------------------------+

DATETIME_DIFF

DATETIME_DIFF(datetime_expression_a, datetime_expression_b, part)

Description

Returns the number of whole specified part intervals between two DATETIME objects (datetime_expression_a - datetime_expression_b). If the first DATETIME is earlier than the second one, the output is negative. Throws an error if the computation overflows the result type, such as if the difference in microseconds between the two DATETIME objects would overflow an INT64 value.

DATETIME_DIFF supports the following values for part:

  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAY
  • WEEK: This date part begins on Sunday.
  • WEEK(<WEEKDAY>): This date part begins on WEEKDAY. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK: Uses ISO 8601 week boundaries. ISO weeks begin on Monday.
  • MONTH
  • QUARTER
  • YEAR