Array functions

GoogleSQL for BigQuery supports the following array functions.

Function list

Name	Summary
ARRAY	Produces an array with one element for each row in a subquery.
ARRAY_AGG	Gets an array of values. For more information, see Aggregate functions.
ARRAY_CONCAT	Concatenates one or more arrays with the same element type into a single array.
ARRAY_CONCAT_AGG	Concatenates arrays and returns a single array as a result. For more information, see Aggregate functions.
ARRAY_FIRST	Gets the first element in an array.
ARRAY_LAST	Gets the last element in an array.
ARRAY_LENGTH	Gets the number of elements in an array.
ARRAY_REVERSE	Reverses the order of elements in an array.
ARRAY_SLICE	Produces an array containing zero or more consecutive elements from an input array.
ARRAY_TO_STRING	Produces a concatenation of the elements in an array as a STRING value.
GENERATE_ARRAY	Generates an array of values in a range.
GENERATE_DATE_ARRAY	Generates an array of dates in a range.
GENERATE_RANGE_ARRAY	Splits a range into an array of subranges. For more information, see Range functions.
GENERATE_TIMESTAMP_ARRAY	Generates an array of timestamps in a range.
JSON_ARRAY	Creates a JSON array. For more information, see JSON functions.
JSON_ARRAY_APPEND	Appends JSON data to the end of a JSON array. For more information, see JSON functions.
JSON_ARRAY_INSERT	Inserts JSON data into a JSON array. For more information, see JSON functions.
JSON_EXTRACT_ARRAY	(Deprecated) Extracts a JSON array and converts it to a SQL ARRAY<JSON-formatted STRING> or ARRAY<JSON> value. For more information, see JSON functions.
JSON_EXTRACT_STRING_ARRAY	(Deprecated) Extracts a JSON array of scalar values and converts it to a SQL ARRAY<STRING> value. For more information, see JSON functions.
JSON_QUERY_ARRAY	Extracts a JSON array and converts it to a SQL ARRAY<JSON-formatted STRING> or ARRAY<JSON> value. For more information, see JSON functions.
JSON_VALUE_ARRAY	Extracts a JSON array of scalar values and converts it to a SQL ARRAY<STRING> value. For more information, see JSON functions.
RANGE_BUCKET	Scans through a sorted array and returns the 0-based position of a point's upper bound. For more information, see Mathematical 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 aren't 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 that GoogleSQL doesn't 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[, ...])

Description

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

The function returns NULL if any input argument is NULL.

Note: You can also use the || concatenation operator to concatenate arrays.

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_FIRST

Preview

This product or feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of the Service Specific Terms. Pre-GA products and features are available "as is" and might have limited support. For more information, see the launch stage descriptions.

Note: To provide feedback or request support for this feature, send an email to [e-mail].

ARRAY_FIRST(array_expression)

Description

Takes an array and returns the first element in the array.

Produces an error if the array is empty.

Returns NULL if array_expression is NULL.

Note: To get the last element in an array, see ARRAY_LAST.

Return type

Matches the data type of elements in array_expression.

Example

SELECT ARRAY_FIRST(['a','b','c','d']) as first_element

/*---------------*
 | first_element |
 +---------------+
 | a             |
 *---------------*/

ARRAY_LAST

Preview

This product or feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of the Service Specific Terms. Pre-GA products and features are available "as is" and might have limited support. For more information, see the launch stage descriptions.

Note: To provide feedback or request support for this feature, send an email to [e-mail].

ARRAY_LAST(array_expression)

Description

Takes an array and returns the last element in the array.

Produces an error if the array is empty.

Returns NULL if array_expression is NULL.

Note: To get the first element in an array, see ARRAY_FIRST.

Return type

Matches the data type of elements in array_expression.

Example

SELECT ARRAY_LAST(['a','b','c','d']) as last_element

/*---------------*
 | last_element  |
 +---------------+
 | d             |
 *---------------*/

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

SELECT
  ARRAY_LENGTH(["coffee", NULL, "milk" ]) AS size_a,
  ARRAY_LENGTH(["cake", "pie"]) AS size_b;

/*--------+--------*
 | size_a | size_b |
 +--------+--------+
 | 3      | 2      |
 *--------+--------*/

ARRAY_REVERSE

ARRAY_REVERSE(value)

Description

Returns the input ARRAY with elements in reverse order.

Return type

ARRAY

Examples

SELECT ARRAY_REVERSE([1, 2, 3]) AS reverse_arr

/*-------------*
 | reverse_arr |
 +-------------+
 | [3, 2, 1]   |
 *-------------*/

ARRAY_SLICE

Preview

This product or feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of the Service Specific Terms. Pre-GA products and features are available "as is" and might have limited support. For more information, see the launch stage descriptions.

Note: To provide feedback or request support for this feature, send an email to [e-mail].

ARRAY_SLICE(array_to_slice, start_offset, end_offset)

Description

Returns an array containing zero or more consecutive elements from the input array.

• array_to_slice: The array that contains the elements you want to slice.
• start_offset: The inclusive starting offset.
• end_offset: The inclusive ending offset.

An offset can be positive or negative. A positive offset starts from the beginning of the input array and is 0-based. A negative offset starts from the end of the input array. Out-of-bounds offsets are supported. Here are some examples:

Input offset	Final offset in array	Notes
0	['a', 'b', 'c', 'd']	The final offset is 0.
3	['a', 'b', 'c', 'd']	The final offset is 3.
5	['a', 'b', 'c', 'd']	Because the input offset is out of bounds, the final offset is 3 (array length - 1).
-1	['a', 'b', 'c', 'd']	Because a negative offset is used, the offset starts at the end of the array. The final offset is 3 (array length - 1).
-2	['a', 'b', 'c', 'd']	Because a negative offset is used, the offset starts at the end of the array. The final offset is 2 (array length - 2).
-4	['a', 'b', 'c', 'd']	Because a negative offset is used, the offset starts at the end of the array. The final offset is 0 (array length - 4).
-5	['a', 'b', 'c', 'd']	Because the offset is negative and out of bounds, the final offset is 0 (array length - array length).

Additional details:

• The input array can contain NULL elements. NULL elements are included in the resulting array.
• Returns NULL if array_to_slice, start_offset, or end_offset is NULL.
• Returns an empty array if array_to_slice is empty.
• Returns an empty array if the position of the start_offset in the array is after the position of the end_offset.

Return type

ARRAY

Examples

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 1, 3) AS result

/*-----------*
 | result    |
 +-----------+
 | [b, c, d] |
 *-----------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], -1, 3) AS result

/*-----------*
 | result    |
 +-----------+
 | []        |
 *-----------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 1, -3) AS result

/*--------*
 | result |
 +--------+
 | [b, c] |
 *--------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], -1, -3) AS result

/*-----------*
 | result    |
 +-----------+
 | []        |
 *-----------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], -3, -1) AS result

/*-----------*
 | result    |
 +-----------+
 | [c, d, e] |
 *-----------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 3, 3) AS result

/*--------*
 | result |
 +--------+
 | [d]    |
 *--------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], -3, -3) AS result

/*--------*
 | result |
 +--------+
 | [c]    |
 *--------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 1, 30) AS result

/*--------------*
 | result       |
 +--------------+
 | [b, c, d, e] |
 *--------------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 1, -30) AS result

/*-----------*
 | result    |
 +-----------+
 | []        |
 *-----------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], -30, 30) AS result

/*-----------------*
 | result          |
 +-----------------+
 | [a, b, c, d, e] |
 *-----------------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], -30, -5) AS result

/*--------*
 | result |
 +--------+
 | [a]    |
 *--------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 5, 30) AS result

/*--------*
 | result |
 +--------+
 | []     |
 *--------*/

SELECT ARRAY_SLICE(['a', 'b', 'c', 'd', 'e'], 1, NULL) AS result

/*-----------*
 | result    |
 +-----------+
 | NULL      |
 *-----------*/

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 isn't used, the function omits the NULL value and its preceding delimiter.

Return type

STRING

Examples

SELECT ARRAY_TO_STRING(['coffee', 'tea', 'milk', NULL], '--', 'MISSING') AS text

/*--------------------------------*
 | text                           |
 +--------------------------------+
 | coffee--tea--milk--MISSING     |
 *--------------------------------*/

SELECT ARRAY_TO_STRING(['cake', 'pie', NULL], '--', 'MISSING') AS text

/*--------------------------------*
 | text                           |
 +--------------------------------+
 | 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
• BIGNUMERIC
• 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

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] |
 *--------------------------------------------------------------------------*/

Supplemental materials

OFFSET and ORDINAL

For information about using OFFSET and ORDINAL with arrays, see Array subscript operator and Accessing array elements.