Lexical structure and syntax

A BigQuery statement comprises a series of tokens. Tokens include identifiers, quoted identifiers, literals, keywords, operators, and special characters. You can separate tokens with comments or whitespace such as spaces, backspaces, tabs, or newlines.

Identifiers

Identifiers are names that are associated with columns, tables, path expressions, and more. They can be unquoted or quoted and some are case-sensitive.

Unquoted identifiers

  • Must begin with a letter or an underscore (_) character.
  • Subsequent characters can be letters, numbers, underscores (_), and dashes, but additional rules apply for dashes (see the next rule).
  • Single dashes can be used with most unquoted identifiers, but not at the beginning or end.

    When you use dashes in an unquoted identifier, you essentially combine an unquoted identifier with one or more unquoted identifiers and numbers. When using dashes, you must generally follow this structure:

    unquoted_identifier[-{ unquoted_identifier | number }][...]
    

    For example: foo-bar, foo-22, foo-22-bar

    Dashes cannot be used in fieldnames.

Quoted identifiers

  • Must be enclosed by backtick (`) characters.
  • Can contain any characters, including spaces and symbols.
  • Cannot be empty.
  • Have the same escape sequences as string literals.
  • If an identifier is the same as a reserved keyword, the identifier must be quoted. For example, the identifier FROM must be quoted. Additional rules apply for path expressions.

Identifier examples

Path expression examples:

-- Valid. _5abc and dataField are valid identifiers.
_5abc.dataField

-- Valid. `5abc` and dataField are valid identifiers.
`5abc`.dataField

-- Invalid. 5abc is an invalid identifier because it is unquoted and starts
-- with a number rather than a letter or underscore.
5abc.dataField

-- Valid. abc5 and dataField are valid identifiers.
abc5.dataField

-- Invalid. abc5! is an invalid identifier because it is unquoted and contains
-- a character that is not a letter, number, or underscore.
abc5!.dataField

-- Valid. `GROUP` and dataField are valid identifiers.
`GROUP`.dataField

-- Invalid. GROUP is an invalid identifier because it is unquoted and is a
-- stand-alone reserved keyword.
GROUP.dataField

-- Valid. abc5 and GROUP are valid identifiers.
abc5.GROUP

Function examples:

-- Valid. dataField is a valid identifier in a function called foo().
foo().dataField

Array access operation examples:

-- Valid. dataField is a valid identifier in an array called items.
items[OFFSET(3)].dataField

Named query parameter examples:

-- Valid. param and dataField are valid identifiers.
@param.dataField

Table name examples:

-- Valid table path.
myproject.mydatabase.mytable287
-- Valid table path.
myproject287.mydatabase.mytable
-- Invalid table path. The project name starts with a number and is unquoted.
287myproject.mydatabase.mytable
-- Invalid table name. The table name is unquoted and is not a valid
-- dashed identifier, as the part after the dash is neither a number nor
-- an identifier starting with a letter or an underscore.
mytable-287a
-- Valid table path.
my-project.mydataset.mytable
-- Valid table name.
my-table
-- Invalid table path because the dash is not in the first part
-- of the path.
myproject.mydataset.my-table
-- Invalid table path because a dataset name cannot contain dashes.
my-dataset.mytable

Path expressions

A path expression describes how to navigate to an object in a graph of objects and generally follows this structure:

path:
  [path_expression][. ...]

path_expression:
  [first_part]/subsequent_part[ { / | : | - } subsequent_part ][...]

first_part:
  { unquoted_identifier | quoted_identifier }

subsequent_part:
  { unquoted_identifier | quoted_identifier | number }
  • path: A graph of one or more objects.
  • path_expression: An object in a graph of objects.
  • first_part: A path expression can start with a quoted or unquoted identifier. If the path expressions starts with a reserved keyword, it must be a quoted identifier.
  • subsequent_part: Subsequent parts of a path expression can include non-identifiers, such as reserved keywords. If a subsequent part of a path expressions starts with a reserved keyword, it may be quoted or unquoted.

Examples:

foo.bar
foo.bar/25
foo/bar:25
foo/bar/25-31
/foo/bar
/25/foo/bar

Table names

A table name represents the name of a table.

Table names can be quoted identifiers or unquoted identifiers. If unquoted:

  • Unquoted identifiers support dashes when referenced in a FROM or TABLE clause. Only the first identifier in the table path (the project ID or the table name) can have dashes. Dashes are not supported in datasets.

A table name can be a fully qualified table name (table path) that includes up to three quoted or unquoted identifiers:

For example: myproject.mydataset.mytable

Table names can be path expressions.

Examples:

my-project.mydataset.mytable
mydataset.mytable
my-table
mytable
`287mytable`

Column names

A column name represents the name of a column in a table.

  • Column names can be quoted identifiers or unquoted identifiers.
  • If unquoted, identifiers support dashed identifiers when referenced in a FROM or TABLE clause.
  • Column names have additional rules.

Examples:

columnA
column-a
`287column`

Literals

A literal represents a constant value of a built-in data type. Some, but not all, data types can be expressed as literals.

String and bytes literals

Both string and bytes literals must be quoted, either with single (') or double (") quotation marks, or triple-quoted with groups of three single (''') or three double (""") quotation marks.

Quoted literals:

Literal Examples Description
Quoted string
  • "abc"
  • "it's"
  • 'it\'s'
  • 'Title: "Boy"'
Quoted strings enclosed by single (') quotes can contain unescaped double (") quotes, as well as the inverse.
Backslashes (\) introduce escape sequences. See the Escape Sequences table below.
Quoted strings cannot contain newlines, even when preceded by a backslash (\).
Triple-quoted string
  • """abc"""
  • '''it's'''
  • '''Title:"Boy"'''
  • '''two
    lines'''
  • '''why\?'''
Embedded newlines and quotes are allowed without escaping - see fourth example.
Backslashes (\) introduce escape sequences. See Escape Sequences table below.
A trailing unescaped backslash (\) at the end of a line is not allowed.
End the string with three unescaped quotes in a row that match the starting quotes.
Raw string
  • R"abc+"
  • r'''abc+'''
  • R"""abc+"""
  • r'f\(abc,(.*),def\)'
Quoted or triple-quoted literals that have the raw string literal prefix (r or R) are interpreted as raw/regex strings.
Backslash characters (\) do not act as escape characters. If a backslash followed by another character occurs inside the string literal, both characters are preserved.
A raw string cannot end with an odd number of backslashes.
Raw strings are useful for constructing regular expressions.

Prefix characters (r, R, b, B) are optional for quoted or triple-quoted strings, and indicate that the string is a raw/regex string or a byte sequence, respectively. For example, b'abc' and b'''abc''' are both interpreted as type bytes. Prefix characters are case insensitive.

Quoted literals with prefixes:

Literal Example Description
Bytes
  • B"abc"
  • B'''abc'''
  • b"""abc"""
Quoted or triple-quoted literals that have the bytes literal prefix (b or B) are interpreted as bytes.
Raw bytes
  • br'abc+'
  • RB"abc+"
  • RB'''abc'''
The r and b prefixes can be combined in any order. For example, rb'abc*' is equivalent to br'abc*'.

The table below lists all valid escape sequences for representing non-alphanumeric characters in string and byte literals. Any sequence not in this table produces an error.

Escape Sequence Description
\a Bell
\b Backspace
\f Formfeed
\n Newline
\r Carriage Return
\t Tab
\v Vertical Tab
\\ Backslash (\)
\? Question Mark (?)
\" Double Quote (")
\' Single Quote (')
\` Backtick (`)
\ooo Octal escape, with exactly 3 digits (in the range 0–7). Decodes to a single Unicode character (in string literals) or byte (in bytes literals).
\xhh or \Xhh Hex escape, with exactly 2 hex digits (0–9 or A–F or a–f). Decodes to a single Unicode character (in string literals) or byte (in bytes literals). Examples:
  • '\x41' == 'A'
  • '\x41B' is 'AB'
  • '\x4' is an error
\uhhhh Unicode escape, with lowercase 'u' and exactly 4 hex digits. Valid only in string literals or identifiers.
Note that the range D800-DFFF is not allowed, as these are surrogate unicode values.
\Uhhhhhhhh Unicode escape, with uppercase 'U' and exactly 8 hex digits. Valid only in string literals or identifiers.
The range D800-DFFF is not allowed, as these values are surrogate unicode values. Also, values greater than 10FFFF are not allowed.

Integer literals

Integer literals are either a sequence of decimal digits (0–9) or a hexadecimal value that is prefixed with "0x" or "0X". Integers can be prefixed by "+" or "-" to represent positive and negative values, respectively. Examples:

123
0xABC
-123

An integer literal is interpreted as an INT64.

NUMERIC literals

You can construct NUMERIC literals using the NUMERIC keyword followed by a floating point value in quotes.

Examples:

SELECT NUMERIC '0';
SELECT NUMERIC '123456';
SELECT NUMERIC '-3.14';
SELECT NUMERIC '-0.54321';
SELECT NUMERIC '1.23456e05';
SELECT NUMERIC '-9.876e-3';

BIGNUMERIC literals

You can construct BIGNUMERIC literals using the BIGNUMERIC keyword followed by a floating point value in quotes.

Examples:

SELECT BIGNUMERIC '0';
SELECT BIGNUMERIC '123456';
SELECT BIGNUMERIC '-3.14';
SELECT BIGNUMERIC '-0.54321';
SELECT BIGNUMERIC '1.23456e05';
SELECT BIGNUMERIC '-9.876e-3';

Floating point literals

Syntax options:

[+-]DIGITS.[DIGITS][e[+-]DIGITS]
[DIGITS].DIGITS[e[+-]DIGITS]
DIGITSe[+-]DIGITS

DIGITS represents one or more decimal numbers (0 through 9) and e represents the exponent marker (e or E).

Examples:

123.456e-67
.1E4
58.
4e2

Numeric literals that contain either a decimal point or an exponent marker are presumed to be type double.

Implicit coercion of floating point literals to float type is possible if the value is within the valid float range.

There is no literal representation of NaN or infinity, but the following case-insensitive strings can be explicitly cast to float:

  • "NaN"
  • "inf" or "+inf"
  • "-inf"

Array literals

Array literals are comma-separated lists of elements enclosed in square brackets. The ARRAY keyword is optional, and an explicit element type T is also optional.

Examples:

[1, 2, 3]
['x', 'y', 'xy']
ARRAY[1, 2, 3]
ARRAY<string>['x', 'y', 'xy']
ARRAY<int64>[]

Struct literals

A struct literal is a struct whose fields are all literals. Struct literals can be written using any of the syntaxes for constructing a struct (tuple syntax, typeless struct syntax, or typed struct syntax).

Note that tuple syntax requires at least two fields, in order to distinguish it from an ordinary parenthesized expression. To write a struct literal with a single field, use typeless struct syntax or typed struct syntax.

Example Output Type
(1, 2, 3) STRUCT<INT64, INT64, INT64>
(1, 'abc') STRUCT<INT64, STRING>
STRUCT(1 AS foo, 'abc' AS bar) STRUCT<foo INT64, bar STRING>
STRUCT<INT32, INT64>(1, 2) STRUCT<INT32, INT64>
STRUCT(1) STRUCT<INT64>
STRUCT<INT64>(1) STRUCT<INT64>

Date literals

Syntax:

DATE 'YYYY-M[M]-D[D]'

Date literals contain the DATE keyword followed by a string literal that conforms to the canonical date format, enclosed in single quotation marks. Date literals support a range between the years 1 and 9999, inclusive. Dates outside of this range are invalid.

For example, the following date literal represents September 27, 2014:

DATE '2014-09-27'

String literals in canonical date format also implicitly coerce to DATE type when used where a DATE-type expression is expected. For example, in the query

SELECT * FROM foo WHERE date_col = "2014-09-27"

the string literal "2014-09-27" will be coerced to a date literal.

Time literals

Syntax:

TIME '[H]H:[M]M:[S]S[.DDDDDD]'

Time literals contain the TIME keyword and a string literal that conforms to the canonical time format, enclosed in single quotation marks.

For example, the following time represents 12:30 p.m.:

TIME '12:30:00.45'

Datetime literals

Syntax:

DATETIME 'YYYY-[M]M-[D]D [[H]H:[M]M:[S]S[.DDDDDD]]'

Datetime literals contain the DATETIME keyword and a string literal that conforms to the canonical datetime format, enclosed in single quotation marks.

For example, the following datetime represents 12:30 p.m. on September 27, 2014:

DATETIME '2014-09-27 12:30:00.45'

Datetime literals support a range between the years 1 and 9999, inclusive. Datetimes outside of this range are invalid.

String literals with the canonical datetime format implicitly coerce to a datetime literal when used where a datetime expression is expected.

For example:

SELECT * FROM foo
WHERE datetime_col = "2014-09-27 12:30:00.45"

In the query above, the string literal "2014-09-27 12:30:00.45" is coerced to a datetime literal.

A datetime literal can also include the optional character T or t. This is a flag for time and is used as a separator between the date and time. If you use this character, a space can't be included before or after it. These are valid:

DATETIME '2014-09-27T12:30:00.45'
DATETIME '2014-09-27t12:30:00.45'

Timestamp literals

Syntax:

TIMESTAMP 'YYYY-[M]M-[D]D [[H]H:[M]M:[S]S[.DDDDDD] [timezone]]'

Timestamp literals contain the TIMESTAMP keyword and a string literal that conforms to the canonical timestamp format, enclosed in single quotation marks.

Timestamp literals support a range between the years 1 and 9999, inclusive. Timestamps outside of this range are invalid.

A timestamp literal can include a numerical suffix to indicate the time zone:

TIMESTAMP '2014-09-27 12:30:00.45-08'

If this suffix is absent, the default time zone, UTC, is used.

For example, the following timestamp represents 12:30 p.m. on September 27, 2014 in the default time zone, UTC:

TIMESTAMP '2014-09-27 12:30:00.45'

For more information about time zones, see Time zone.

String literals with the canonical timestamp format, including those with time zone names, implicitly coerce to a timestamp literal when used where a timestamp expression is expected. For example, in the following query, the string literal "2014-09-27 12:30:00.45 America/Los_Angeles" is coerced to a timestamp literal.

SELECT * FROM foo
WHERE timestamp_col = "2014-09-27 12:30:00.45 America/Los_Angeles"

A timestamp literal can include these optional characters:

  • T or t: A flag for time. Use as a separator between the date and time.
  • Z or z: A flag for the default timezone. This cannot be used with [timezone].

If you use one of these characters, a space can't be included before or after it. These are valid:

TIMESTAMP '2017-01-18T12:34:56.123456Z'
TIMESTAMP '2017-01-18t12:34:56.123456'
TIMESTAMP '2017-01-18 12:34:56.123456z'
TIMESTAMP '2017-01-18 12:34:56.123456Z'

Time zone

Since timestamp literals must be mapped to a specific point in time, a time zone is necessary to correctly interpret a literal. If a time zone is not specified as part of the literal itself, then BigQuery uses the default time zone value, which the BigQuery implementation sets.

BigQuery represents time zones using strings in the following canonical format, which represents the offset from Coordinated Universal Time (UTC).

Format:

(+|-)H[H][:M[M]]

Examples:

'-08:00'
'-8:15'
'+3:00'
'+07:30'
'-7'

Time zones can also be expressed using string time zone names from the tz database. For a less comprehensive but simpler reference, see the List of tz database time zones on Wikipedia. Canonical time zone names have the format <continent/[region/]city>, such as America/Los_Angeles.

Example:

TIMESTAMP '2014-09-27 12:30:00 America/Los_Angeles'
TIMESTAMP '2014-09-27 12:30:00 America/Argentina/Buenos_Aires'

Interval literals

Syntax:

INTERVAL 'N' datetime_part
INTERVAL '[Y]-[M] [D] [H]:[M]:[S].[F]' datetime_part TO datetime_part

datetime_part is one of YEAR, MONTH, DAY, HOUR, MINUTE or SECOND.

Interval literals come in two forms. The first form has a single datetime part. For example:

INTERVAL '5' DAY
INTERVAL '0.001' SECOND

The second form allows multiple consecutive datetime parts. For example:

-- 10 hours, 20 minutes, 30 seconds
INTERVAL '10:20:30' HOUR TO SECOND
-- 1 year, 2 months
INTERVAL '1-2' YEAR TO MONTH
-- 1 month, 15 days
INTERVAL '1 15' MONTH TO DAY
-- 1 day, 5 hours, 30 minutes
INTERVAL '1 5:30' DAY TO MINUTE

JSON literals

Syntax:

JSON 'json_formatted_data'

A JSON literal represents JSON-formatted data.

Example:

JSON '
{
  "id": 10,
  "type": "fruit",
  "name": "apple",
  "on_menu": true,
  "recipes":
    {
      "salads":
      [
        { "id": 2001, "type": "Walnut Apple Salad" },
        { "id": 2002, "type": "Apple Spinach Salad" }
      ],
      "desserts":
      [
        { "id": 3001, "type": "Apple Pie" },
        { "id": 3002, "type": "Apple Scones" },
        { "id": 3003, "type": "Apple Crumble" }
      ]
    }
}
'

Case sensitivity

BigQuery follows these rules for case sensitivity:

Category Case Sensitive? Notes
Keywords No  
Built-in Function names No  
User-Defined Function names Yes  
Table names Yes  
Column names No  
String values Yes
String comparisons Yes  
Aliases within a query No  
Regular expression matching See Notes Regular expression matching is case sensitive by default, unless the expression itself specifies that it should be case insensitive.
LIKE matching Yes  

Reserved keywords

Keywords are a group of tokens that have special meaning in the BigQuery language, and have the following characteristics:

  • Keywords cannot be used as identifiers unless enclosed by backtick (`) characters.
  • Keywords are case insensitive.

BigQuery has the following reserved keywords.

ALL
AND
ANY
ARRAY
AS
ASC
ASSERT_ROWS_MODIFIED
AT
BETWEEN
BY
CASE
CAST
COLLATE
CONTAINS
CREATE
CROSS
CUBE
CURRENT
DEFAULT
DEFINE
DESC
DISTINCT
ELSE
END
ENUM
ESCAPE
EXCEPT
EXCLUDE
EXISTS
EXTRACT
FALSE
FETCH
FOLLOWING
FOR
FROM
FULL
GROUP
GROUPING
GROUPS
HASH
HAVING
IF
IGNORE
IN
INNER
INTERSECT
INTERVAL
INTO
IS
JOIN
LATERAL
LEFT
LIKE
LIMIT
LOOKUP
MERGE
NATURAL
NEW
NO
NOT
NULL
NULLS
OF
ON
OR
ORDER
OUTER
OVER
PARTITION
PRECEDING
PROTO
QUALIFY
RANGE
RECURSIVE
RESPECT
RIGHT
ROLLUP
ROWS
SELECT
SET
SOME
STRUCT
TABLESAMPLE
THEN
TO
TREAT
TRUE
UNBOUNDED
UNION
UNNEST
USING
WHEN
WHERE
WINDOW
WITH
WITHIN

Terminating semicolons

You can optionally use a terminating semicolon (;) when you submit a query string statement through an Application Programming Interface (API).

In a request containing multiple statements, you must separate statements with semicolons, but the semicolon is generally optional after the final statement. Some interactive tools require statements to have a terminating semicolon.

Trailing commas

You can optionally use a trailing comma (,) at the end of a column list in a SELECT statement. You might have a trailing comma as the result of programmatically creating a column list.

Example

SELECT name, release_date, FROM Books

Query parameters

You can use query parameters to substitute arbitrary expressions. However, query parameters cannot be used to substitute identifiers, column names, table names, or other parts of the query itself. Query parameters are defined outside of the query statement.

Client APIs allow the binding of parameter names to values; the query engine substitutes a bound value for a parameter at execution time.

Query parameters cannot be used in the SQL body of these statements: CREATE FUNCTION, CREATE VIEW, CREATE MATERIALIZED VIEW, and CREATE PROCEDURE.

Named query parameters

Syntax:

@parameter_name

A named query parameter is denoted using an identifier preceded by the @ character. Named query parameters cannot be used alongside positional query parameters.

A named query parameter can start with an identifier or a reserved keyword. An identifier can be unquoted or quoted.

Example:

This example returns all rows where LastName is equal to the value of the named query parameter myparam.

SELECT * FROM Roster WHERE LastName = @myparam

Positional query parameters

Positional query parameters are denoted using the ? character. Positional parameters are evaluated by the order in which they are passed in. Positional query parameters cannot be used alongside named query parameters.

Example:

This query returns all rows where LastName and FirstName are equal to the values passed into this query. The order in which these values are passed in matters. If the last name is passed in first, followed by the first name, the expected results will not be returned.

SELECT * FROM Roster WHERE FirstName = ? and LastName = ?

Comments

Comments are sequences of characters that the parser ignores. BigQuery supports the following types of comments.

Single-line comments

Use a single-line comment if you want the comment to appear on a line by itself.

Examples

# this is a single-line comment
SELECT book FROM library;
-- this is a single-line comment
SELECT book FROM library;
/* this is a single-line comment */
SELECT book FROM library;
SELECT book FROM library
/* this is a single-line comment */
WHERE book = "Ulysses";

Inline comments

Use an inline comment if you want the comment to appear on the same line as a statement. A comment that is prepended with # or -- must appear to the right of a statement.

Examples

SELECT book FROM library; # this is an inline comment
SELECT book FROM library; -- this is an inline comment
SELECT book FROM library; /* this is an inline comment */
SELECT book FROM library /* this is an inline comment */ WHERE book = "Ulysses";

Multiline comments

Use a multiline comment if you need the comment to span multiple lines. Nested multiline comments are not supported.

Examples

SELECT book FROM library
/*
  This is a multiline comment
  on multiple lines
*/
WHERE book = "Ulysses";
SELECT book FROM library
/* this is a multiline comment
on two lines */
WHERE book = "Ulysses";