Array functions

GoogleSQL supports the following array functions.

Function list

value.
<br>For more information, see <a href="https://github.com/google/googlesql/blob/master/docs/json_functions.md">JSON functions</a>.

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<br>For more information, see <a href="https://github.com/google/googlesql/blob/master/docs/json_functions.md">JSON functions</a>.

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_AVG

ARRAY_AVG(input_array)

Description

Returns the average of non-NULL values in an array.

Caveats:

• If the array is NULL, empty, or contains only NULLs, returns NULL.
• If the array contains NaN, returns NaN.
• If the array contains [+|-]Infinity, returns either [+|-]Infinity or NaN.
• If there is numeric overflow, produces an error.
• If a floating-point type is returned, the result is non-deterministic, which means you might receive a different result each time you use this function.

Supported Argument Types

In the input array, ARRAY<T>, T can represent one of the following data types:

• Any numeric input type
• INTERVAL

Return type

The return type depends upon T in the input array:

Examples

SELECT ARRAY_AVG([0, 2, NULL, 4, 4, 5]) as avg

/*-----+
 | avg |
 +-----+
 | 3   |
 +-----*/

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_FILTER

ARRAY_FILTER(array_expression, lambda_expression)

lambda_expression:
  {
    element_alias -> boolean_expression
    | (element_alias, index_alias) -> boolean_expression
  }

Description

Takes an array, filters out unwanted elements, and returns the results in a new array.

• array_expression: The array to filter.
• lambda_expression: Each element in array_expression is evaluated against the lambda expression. If the expression evaluates to FALSE or NULL, the element is removed from the resulting array.
• element_alias: An alias that represents an array element.
• index_alias: An alias that represents the zero-based offset of the array element.
• boolean_expression: The predicate used to filter the array elements.

Returns NULL if the array_expression is NULL.

Return type

ARRAY

Example

SELECT
  ARRAY_FILTER([1 ,2, 3], e -> e > 1) AS a1,
  ARRAY_FILTER([0, 2, 3], (e, i) -> e > i) AS a2;

/*-------+-------+
 | a1    | a2    |
 +-------+-------+
 | [2,3] | [2,3] |
 +-------+-------*/

ARRAY_FIRST

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_INCLUDES

• Signature 1: ARRAY_INCLUDES(array_to_search, search_value)
• Signature 2: ARRAY_INCLUDES(array_to_search, lambda_expression)

Signature 1

ARRAY_INCLUDES(array_to_search, search_value)

Description

Takes an array and returns TRUE if there is an element in the array that is equal to the search_value.

• array_to_search: The array to search.
• search_value: The element to search for in the array.

Returns NULL if array_to_search or search_value is NULL.

Return type

BOOL

Example

In the following example, the query first checks to see if 0 exists in an array. Then the query checks to see if 1 exists in an array.

SELECT
  ARRAY_INCLUDES([1, 2, 3], 0) AS a1,
  ARRAY_INCLUDES([1, 2, 3], 1) AS a2;

/*-------+------+
 | a1    | a2   |
 +-------+------+
 | false | true |
 +-------+------*/

Signature 2

ARRAY_INCLUDES(array_to_search, lambda_expression)

lambda_expression: element_alias -> boolean_expression

Description

Takes an array and returns TRUE if the lambda expression evaluates to TRUE for any element in the array.

• array_to_search: The array to search.
• lambda_expression: Each element in array_to_search is evaluated against the lambda expression.
• element_alias: An alias that represents an array element.
• boolean_expression: The predicate used to evaluate the array elements.

Returns NULL if array_to_search is NULL.

Return type

BOOL

Example

In the following example, the query first checks to see if any elements that are greater than 3 exist in an array (e > 3). Then the query checks to see if any elements that are greater than 0 exist in an array (e > 0).

SELECT
  ARRAY_INCLUDES([1, 2, 3], e -> e > 3) AS a1,
  ARRAY_INCLUDES([1, 2, 3], e -> e > 0) AS a2;

/*-------+------+
 | a1    | a2   |
 +-------+------+
 | false | true |
 +-------+------*/

ARRAY_INCLUDES_ALL

ARRAY_INCLUDES_ALL(array_to_search, search_values)

Description

Takes an array to search and an array of search values. Returns TRUE if all search values are in the array to search, otherwise returns FALSE.

• array_to_search: The array to search.
• search_values: The array that contains the elements to search for.

Returns NULL if array_to_search or search_values is NULL.

Return type

BOOL

Example

In the following example, the query first checks to see if 3, 4, and 5 exists in an array. Then the query checks to see if 4, 5, and 6 exists in an array.

SELECT
  ARRAY_INCLUDES_ALL([1,2,3,4,5], [3,4,5]) AS a1,
  ARRAY_INCLUDES_ALL([1,2,3,4,5], [4,5,6]) AS a2;

/*------+-------+
 | a1   | a2    |
 +------+-------+
 | true | false |
 +------+-------*/

ARRAY_INCLUDES_ANY

ARRAY_INCLUDES_ANY(array_to_search, search_values)

Description

Takes an array to search and an array of search values. Returns TRUE if any search values are in the array to search, otherwise returns FALSE.

• array_to_search: The array to search.
• search_values: The array that contains the elements to search for.

Returns NULL if array_to_search or search_values is NULL.

Return type

BOOL

Example

In the following example, the query first checks to see if 3, 4, or 5 exists in an array. Then the query checks to see if 4, 5, or 6 exists in an array.

SELECT
  ARRAY_INCLUDES_ANY([1,2,3], [3,4,5]) AS a1,
  ARRAY_INCLUDES_ANY([1,2,3], [4,5,6]) AS a2;

/*------+-------+
 | a1   | a2    |
 +------+-------+
 | true | false |
 +------+-------*/

ARRAY_IS_DISTINCT

ARRAY_IS_DISTINCT(value)

Description

Returns TRUE if the array contains no repeated elements, using the same equality comparison logic as SELECT DISTINCT.

Return type

BOOL

Examples

SELECT ARRAY_IS_DISTINCT([1, 2, 3]) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | true        |
 +-------------*/

SELECT ARRAY_IS_DISTINCT([1, 1, 1]) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | false       |
 +-------------*/

SELECT ARRAY_IS_DISTINCT([1, 2, NULL]) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | true        |
 +-------------*/

SELECT ARRAY_IS_DISTINCT([1, 1, NULL]) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | false       |
 +-------------*/

SELECT ARRAY_IS_DISTINCT([1, NULL, NULL]) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | false       |
 +-------------*/

SELECT ARRAY_IS_DISTINCT([]) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | true        |
 +-------------*/

SELECT ARRAY_IS_DISTINCT(NULL) AS is_distinct

/*-------------+
 | is_distinct |
 +-------------+
 | NULL        |
 +-------------*/

ARRAY_LAST

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_MAX

ARRAY_MAX(input_array)

Description

Returns the maximum non-NULL value in an array.

Caveats:

• If the array is NULL, empty, or contains only NULLs, returns NULL.
• If the array contains NaN, returns NaN.

Supported Argument Types

In the input array, ARRAY<T>, T can be an orderable data type.

Return type

The same data type as T in the input array.

Examples

SELECT ARRAY_MAX([8, 37, NULL, 55, 4]) as max

/*-----+
 | max |
 +-----+
 | 55  |
 +-----*/

ARRAY_MIN

ARRAY_MIN(input_array)

Description

Returns the minimum non-NULL value in an array.

Caveats:

• If the array is NULL, empty, or contains only NULLs, returns NULL.
• If the array contains NaN, returns NaN.

Supported Argument Types

In the input array, ARRAY<T>, T can be an orderable data type.

Return type

The same data type as T in the input array.

Examples

SELECT ARRAY_MIN([8, 37, NULL, 4, 55]) as min

/*-----+
 | min |
 +-----+
 | 4   |
 +-----*/

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

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:

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      |
 +-----------*/

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

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

ARRAY_SUM

ARRAY_SUM(input_array)

Description

Returns the sum of non-NULL values in an array.

Caveats:

• If the array is NULL, empty, or contains only NULLs, returns NULL.
• If the array contains NaN, returns NaN.
• If the array contains [+|-]Infinity, returns either [+|-]Infinity or NaN.
• If there is numeric overflow, produces an error.
• If a floating-point type is returned, the result is non-deterministic, which means you might receive a different result each time you use this function.

Supported Argument Types

In the input array, ARRAY<T>, T can represent:

• Any supported numeric data type
• INTERVAL

Return type

The return type depends upon T in the input array:

Examples

SELECT ARRAY_SUM([1, 2, 3, 4, 5, NULL, 4, 3, 2, 1]) as sum

/*-----+
 | sum |
 +-----+
 | 25  |
 +-----*/

ARRAY_TO_STRING

ARRAY_TO_STRING(array_expression, delimiter[, null_text])

Description

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

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 for a function signature with STRING input.
• BYTES for a function signature with BYTES input.

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             |
 +--------------------------------*/

SELECT ARRAY_TO_STRING([b'prefix', b'middle', b'suffix', b'\x00'], b'--') AS data

/*--------------------------------+
 | data                           |
 +--------------------------------+
 | prefix--middle--suffix--\x00   |
 +--------------------------------*/

ARRAY_TRANSFORM

ARRAY_TRANSFORM(array_expression, lambda_expression)

lambda_expression:
  {
    element_alias -> transform_expression
    | (element_alias, index_alias) -> transform_expression
  }

Description

Takes an array, transforms the elements, and returns the results in a new array. The output array always has the same length as the input array.

• array_expression: The array to transform.
• lambda_expression: Each element in array_expression is evaluated against the lambda expression. The evaluation results are returned in a new array.
• element_alias: An alias that represents an array element.
• index_alias: An alias that represents the zero-based offset of the array element.
• transform_expression: The expression used to transform the array elements.

Returns NULL if the array_expression is NULL.

Return type

ARRAY

Example

SELECT
  ARRAY_TRANSFORM([1, 4, 3], e -> e + 1) AS a1,
  ARRAY_TRANSFORM([1, 4, 3], (e, i) -> e + i) AS a2;

/*---------+---------+
 | a1      | a2      |
 +---------+---------+
 | [2,5,4] | [1,5,5] |
 +---------+---------*/

ARRAY_ZIP

ARRAY_ZIP(
  array_input [ AS alias ],
  array_input [ AS alias ][, ... ]
  [, [ transformation => ] value ]
  [, mode => { 'STRICT' | 'TRUNCATE' | 'PAD' } ]
)

Description

Combines the elements from two to four arrays into one array.

Definitions

• array_input: An input ARRAY value to be zipped with the other array inputs. ARRAY_ZIP supports two to four input arrays.

• alias: An alias optionally supplied for an array_input. In the results, the alias is the name of the associated STRUCT field.

• transformation: A named argument with a lambda expression. The lambda expression specifies how elements are combined as they are zipped. This overrides the default STRUCT creation behavior.

• mode: A named argument with a STRING value. Determines how arrays of differing lengths are zipped. If this argument isn't supplied, the function uses STRICT mode. This argument can be one of the following values:

  • STRICT (default): If the length of any array is different from the others, produce an error.

  • TRUNCATE: Truncate longer arrays to match the length of the shortest array.

  • PAD: Pad shorter arrays with NULL values to match the length of the longest array.

Details

• If an array_input or mode is NULL, this function returns NULL, even when mode is STRICT.
• Argument aliases can't be used with the transformation argument.

Return type

• If transformation is used and returns type T, the return type is ARRAY<T>.
• Otherwise, the return type is ARRAY<STRUCT>, with the STRUCT having a number of fields equal to the number of input arrays. Each field's name is either the user-provided alias for the corresponding array_input, or a default alias assigned by the compiler, following the same logic used for naming columns in a SELECT list.

Examples

The following query zips two arrays into one:

SELECT ARRAY_ZIP([1, 2], ['a', 'b']) AS results

/*----------------------+
 | results              |
 +----------------------+
 | [(1, 'a'), (2, 'b')] |
 +----------------------*/

You can give an array an alias. For example, in the following query, the returned array is of type ARRAY<STRUCT<A1, alias_inferred>>, where:

• A1 is the alias provided for array [1, 2].
• alias_inferred is the inferred alias provided for array ['a', 'b'].

WITH T AS (
  SELECT ['a', 'b'] AS alias_inferred
)
SELECT ARRAY_ZIP([1, 2] AS A1, alias_inferred) AS results
FROM T

/*----------------------------------------------------------+
 | results                                                  |
 +----------------------------------------------------------+
 | [{1 A1, 'a' alias_inferred}, {2 A1, 'b' alias_inferred}] |
 +----------------------------------------------------------*/

To provide a custom transformation of the input arrays, use the transformation argument:

SELECT ARRAY_ZIP([1, 2], [3, 4], transformation => (e1, e2) -> (e1 + e2))

/*---------+
 | results |
 +---------+
 | [4, 6]  |
 +---------*/

The argument name transformation isn't required. For example:

SELECT ARRAY_ZIP([1, 2], [3, 4], (e1, e2) -> (e1 + e2))

/*---------+
 | results |
 +---------+
 | [4, 6]  |
 +---------*/

When transformation is provided, the input arrays aren't allowed to have aliases. For example, the following query is invalid:

-- Error: ARRAY_ZIP function with lambda argument doesn't allow providing
-- argument aliases
SELECT ARRAY_ZIP([1, 2], [3, 4] AS alias_not_allowed, (e1, e2) -> (e1 + e2))

To produce an error when arrays with different lengths are zipped, don't add mode, or if you do, set it as STRICT. For example:

-- Error: Unequal array length
SELECT ARRAY_ZIP([1, 2], ['a', 'b', 'c', 'd']) AS results

-- Error: Unequal array length
SELECT ARRAY_ZIP([1, 2], ['a', 'b', 'c', 'd'], mode => 'STRICT') AS results

Use the PAD mode to pad missing values with NULL when input arrays have different lengths. For example:

SELECT ARRAY_ZIP([1, 2], ['a', 'b', 'c', 'd'], [], mode => 'PAD') AS results

/*------------------------------------------------------------------------+
 | results                                                                |
 +------------------------------------------------------------------------+
 | [{1, 'a', NULL}, {2, 'b', NULL}, {NULL, 'c', NULL}, {NULL, 'd', NULL}] |
 +------------------------------------------------------------------------*/

Use the TRUNCATE mode to truncate all arrays that are longer than the shortest array. For example:

SELECT ARRAY_ZIP([1, 2], ['a', 'b', 'c', 'd'], mode => 'TRUNCATE') AS results

/*----------------------+
 | results              |
 +----------------------+
 | [(1, 'a'), (2, 'b')] |
 +----------------------*/

FLATTEN

FLATTEN(array_elements_field_access_expression)

Description

Takes an array of nested data and flattens a specific part of it into a single, flat array with the array elements field access operator. Returns NULL if the input value is NULL. If NULL array elements are encountered, they are added to the resulting array.

There are several ways to flatten nested data into arrays. To learn more, see Flattening nested data into an array.

Return type

ARRAY

Examples

In the following example, all of the arrays for v.sales.quantity are concatenated in a flattened array.

WITH t AS (
  SELECT
  [
    STRUCT([STRUCT([1,2,3] AS quantity), STRUCT([4,5,6] AS quantity)] AS sales),
    STRUCT([STRUCT([7,8] AS quantity), STRUCT([] AS quantity)] AS sales)
  ] AS v
)
SELECT FLATTEN(v.sales.quantity) AS all_values
FROM t;

/*--------------------------+
 | all_values               |
 +--------------------------+
 | [1, 2, 3, 4, 5, 6, 7, 8] |
 +--------------------------*/

In the following example, OFFSET gets the second value in each array and concatenates them.

WITH t AS (
  SELECT
  [
    STRUCT([STRUCT([1,2,3] AS quantity), STRUCT([4,5,6] AS quantity)] AS sales),
    STRUCT([STRUCT([7,8,9] AS quantity), STRUCT([10,11,12] AS quantity)] AS sales)
  ] AS v
)
SELECT FLATTEN(v.sales.quantity[OFFSET(1)]) AS second_values
FROM t;

/*---------------+
 | second_values |
 +---------------+
 | [2, 5, 8, 11] |
 +---------------*/

In the following example, all values for v.price are returned in a flattened array.

WITH t AS (
  SELECT
  [
    STRUCT(1 AS price, 2 AS quantity),
    STRUCT(10 AS price, 20 AS quantity)
  ] AS v
)
SELECT FLATTEN(v.price) AS all_prices
FROM t;

/*------------+
 | all_prices |
 +------------+
 | [1, 10]    |
 +------------*/

For more examples, including how to use protocol buffers with FLATTEN, see the array elements field access operator.

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
• UINT64
• NUMERIC
• BIGNUMERIC
• DOUBLE

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: PICOSECOND, NANOSECOND, 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.