A newer version of this documentation is available.

View Latest

Array Functions

You can use array functions to evaluate arrays, perform computations on elements in an array, and to return a new array based on a transformation.

ARRAY_AGG(expr)

Description

This function returns an array of the non-MISSING group values in the input expr, including NULL values.

Arguments
expr

[Required] The group of elements you wish to output in an array.

Return Values

An array of non-MISSING values.

If the input expression is MISSING or if one of the elements in the array is MISSING, then it returns MISSING.

Example 8: Use ARRAY_AGG to group a list of three items into an array.

SELECT ARRAY_AGG(["abc",1,NULL]) AS array_aggregate;

Results:
[
  {
    "array_aggregate": [
      [
        "abc",
        1,
        null
      ]
    ]
  }
]

ARRAY_APPEND(expr, val1, val2, …)

Description

This function takes an array expr and one or more val arguments to return a new array with the specified val argument(s) appended.

Arguments
expr

[Required] The array to be appended to.

val1, val2, …

[At least 1 is Required] The text string(s) to be appended.

Return Values

A new array with the specified val argument(s) appended.

It requires a minimum of two arguments and returns an error if there are fewer.

If either of the input argument types are MISSING, then it returns MISSING.

If either of the input argument types are NULL, then it returns NULL.

If the expr argument is not an array, then it returns NULL.

If the expr is in the WHERE clause of a partial index, this function lists the expressions that are implicitly covered.

Example 1: Use ARRAY_APPEND to add a user to the Public Likes array.

SELECT ARRAY_APPEND(t.public_likes, "Valerie Smith") AS add_user_likes
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "add_user_likes": [
      "Julius Tromp I",
      "Corrine Hilll",
      "Jaeden McKenzie",
      "Vallie Ryan",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow",
      "Valerie Smith"
    ]
  }
]

ARRAY_AVG(expr)

Description

This function takes an array expr as an argument and returns the arithmetic mean (average) of all the non-NULL number values in the array, or NULL if there are no such values.

Arguments
expr

[Required] The array of numbers to be evaluated.

Return Values

A number representing the arithmetic mean (average) of all the non-NULL number values in the array expression.

If there are no number values in array expr, then it returns NULL.

If the input expr is MISSING, then it returns MISSING.

If the array size of expr is 0 (no elements), then it returns NULL.

Any non-number elements in the array expr are ignored.

Example 2: Use ARRAY_AVG with a set of numbers.

SELECT ARRAY_AVG([0,1,1,2,3,5]) AS array_average;

Results:
[
  {
    "array_average": 2
  }
]

ARRAY_CONCAT(expr1, expr2, …)

Description

This function takes two or more expr arrays and returns a new array after concatenating the input arrays.

Arguments
expression1, expression2, …

[At least 2 are Required] The arrays to be concatenated together.

Return Values

If there are fewer than two arguments, then it returns an error.

If any of the input expr arguments or one of the array elements are MISSING, then it returns MISSING.

If any of the input expr arguments is NULL, then it returns NULL.

If any of the input expr arguments is not an array, then it returns NULL.

Example 3: Use ARRAY_CONCAT to add two people to the Public Likes array.

SELECT ARRAY_CONCAT(t.public_likes, ["John McHill", "Dave Smith"]) AS add_user_likes
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "add_user_likes": [
      "Julius Tromp I",
      "Corrine Hilll",
      "Jaeden McKenzie",
      "Vallie Ryan",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow",
      "John McHill",
      "Dave Smith"
    ]
  }
]

ARRAY_CONTAINS(expr, val)

Description

This functions checks if the array expression contains the specified value.

Arguments
expr

[Required] The array to be searched.

val

[Required] The value that is being searched for.

Return Values

If either of the input argument types are MISSING, then it returns MISSING.

If either of the input argument types are NULL, then it returns NULL.

If the expr argument is not an array, then it returns NULL.

If the array expr contains val, then it returns TRUE; otherwise, it returns FALSE.

Example 4: Use ARRAY_CONTAINS with a Boolean function.

SELECT ARRAY_CONTAINS(t.public_likes, "Vallie Ryan") AS array_contains_value
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "array_contains_value": true
  }
]

ARRAY_COUNT(expr)

Description

This function counts all the non-NULL values in the input expr array.

Arguments
expr

[Required] The array to be searched and evaluate its values.

Return Values

This function returns a count of all the non-NULL values in the array, or zero if there are no such values.

If the expr argument is MISSING, then it returns MISSING.

If the expr argument is NULL, then it returns NULL.

If the expr argument is not an array, then it returns NULL.

Example 5: Use ARRAY_COUNT to count the total hotel reviews.

SELECT ARRAY_COUNT(t.reviews) AS total_reviews
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "total_reviews": 2
  }
]

ARRAY_DISTINCT(expr)

Description

This function returns a new array with distinct elements of the input array expr.

Arguments
expr

[Required] The array of items to be evaluated.

Return Values

An array with distinct elements of the input array expr.

If the input expr is MISSING, it returns MISSING.

If the input expr is a non-array value, it returns NULL.

Example 6: Use ARRAY_DISTINCT with a group of items.

SELECT ARRAY_DISTINCT(["apples","bananas","grapes","oranges","apples","mangoes","bananas"])
AS distinct_fruits;

Results:
[
  {
    "distinct_fruits": [
      "oranges",
      "grapes",
      "bananas",
      "mangoes",
      "apples"
    ]
  }
]

ARRAY_FLATTEN(expr, depth)

Description

This function flattens nested array elements into the top-level array, up to the specified depth.

Arguments
expr

[Required] The multilevel array to be flattened.

depth

[Required] The Integer representing the number of depths to flatten.

Return Value

An array with depth fewer levels than the input array expr.

If one of the arguments is MISSING, it returns MISSING.

If the input expr is a non-array, or if the input depth argument is not an integer, it returns NULL.

Example 7a: Create a 3-level array of numbers to flatten by 1 level.

INSERT INTO default (KEY, value)
             VALUES ("na", {"a":2, "b":[1,2,[31,32,33],4,[[511, 512], 52]]});

SELECT ARRAY_FLATTEN(b,1) AS flatten_by_1level FROM default USE KEYS ["na"];

Results:
[
  {
    "flatten_by_1level": [
      1,
      2,
      31,
      32,
      33,
      4,
      [
        511,
        512
      ],
      52
    ]
  }
]

Example 7b: Flatten the above example by 2 levels.

SELECT ARRAY_FLATTEN(b,2) AS flatten_by_2levels FROM default USE KEYS ["na"];

Results:
[
  {
    "flatten_by_2levels": [
      1,
      2,
      31,
      32,
      33,
      4,
      511,
      512,
      52
    ]
  }
]

ARRAY_IFNULL(expr)

Description

This function parses the input array expr and returns the first non-NULL value in the array.

Arguments
expr

[Required] The array of values to be evaluated.

Return Values

The first non-NULL value in the input array.

If the input expr is MISSING, then it returns MISSING.

If the input expr is a non-array, then it returns NULL.

Example 9: Find the first non-NULL value in an array of items.

SELECT ARRAY_IFNULL( ["","apples","","bananas","grapes","oranges"]) AS check_null;

Results:
[
  {
    "check_null": ""
  }
]

Example 10: Find the first non-null hotel reviewers.

SELECT ARRAY_IFNULL(t.public_likes) AS if_null
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 2;

Results:
[
  {
    "if_null": "Julius Tromp I"
  },
  {
    "if_null": null
  }
]

ARRAY_INSERT(expr, pos, val1, val2, …)

Description

This function inserts the specified value or multiple value items into the specified position in the input array expression, and returns the new array.

Arguments
expr

[Required] The array to insert items into.

pos

[Required] The integer specifying the array position from the left of the input array expr, where the 1st position is 0 (zero).

val1, val2, …

[At least one is Required] The value or multiple value items to insert into the input array expression.

Return Values

An array with the input value or multiple value items inserted into the input array expression at position pos.

If any of the three arguments are MISSING, then it returns MISSING.

If the expr argument is a non-array or if the position argument is not an integer, then it returns NULL.

Example 11: Insert "jsmith" into the 2nd position of the public_likes array.

SELECT ARRAY_INSERT(public_likes, 2, "jsmith") AS insert_val
FROM `travel-sample`
WHERE type = "hotel"
LIMIT 1;

Result:[
  {
    "insert_val": [
      "Julius Tromp I",
      "Corrine Hilll",
      "jsmith",
      "Jaeden McKenzie",
      "Vallie Ryan",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow"
    ]
  }
]

ARRAY_INTERSECT(expr1, expr2, ...)

(Introduced in Couchbase Server 4.5.1)

Description

This function takes two or more arrays and returns the intersection of the input arrays as the result; that is, the array containing values that are present in all of the input arrays.

Arguments
expr1, expr2, …

[At least 2 are Required] The two or more arrays to compare the values of.

Return Values

An array containing the values that are present in all of the input arrays.

If there are no common elements, then it returns an empty array.

If any of the input arguments are MISSING, then it returns MISSING.

If any of the input arguments are non-array values, then it returns NULL.

Example 12: Compare three arrays of fruit for common elements.

SELECT ARRAY_INTERSECT( ["apples","bananas","grapes","orange"], ["apples","orange"], ["apples","grapes"])
AS array_intersection;

Result:
[
  {
    "array_intersection": [
      "apples"
    ]
  }
]

Example 13: Compare three arrays of fruit with no common elements.

SELECT ARRAY_INTERSECT( ["apples","grapes","oranges"], ["apples"],["oranges"],["bananas", "grapes"])
AS array_intersection;

Result:
[
  {
    "array_intersection": []
  }
]

ARRAY_LENGTH(expr)

Description

This function returns the number of elements in the input array.

Arguments
expr

[Required] The array whose elements you want to know the number of.

Return Values

An integer representing the number of elements in the input array.

If the input argument is MISSING, then it returns MISSING.

If the input argument is a non-array value, then it returns NULL.

Example 14: Find how many total public_likes there are in the travel-sample bucket.

SELECT ARRAY_LENGTH(t.public_likes) AS total_likes
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Result:
[
  {
    "total_likes": 8
  }
]

ARRAY_MAX(expr)

Description

This function returns the largest non-NULL, non-MISSING array element, in N1QL collation order.

Arguments
expr

[Required] The array whose elements you want to know the highest value of.

Return Values

The largest non-NULL, non-MISSING array element, in N1QL collation order.

If the input expr is MISSING, then it returns MISSING.

If the input expr is a non-array value, then it returns NULL.

Example 15: Find the maximum (last) value of the public_likes array.

SELECT ARRAY_MAX(t.public_likes) AS max_val
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "max_val": "Vallie Ryan"
  }
]

ARRAY_MIN(expr)

Description

This function returns the smallest non-NULL, non-MISSING array element, in N1QL collation order.

Arguments
expr

[Required] The array whose elements you want to know the lowest value of.

Return Values

The smallest non-NULL, non-MISSING array element, in N1QL collation order.

If the input expr is MISSING, then it returns MISSING.

If the input expr is a non-array value, then it returns NULL.

Example 16: Find the minimum (first) value of the public_likes array.

SELECT ARRAY_MIN(t.public_likes) AS min_val
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "min_val": "Brian Kilback"
  }
]

ARRAY_POSITION(expr, val)

Description

This function returns the first position of the specified value within the array expression.

The array position is zero-based, that is, the first position is 0.

Arguments
expr

[Required] The array you want to search through.

val

[Required] The value you’re searching for and whose position you want to know.

Return Values

An integer representing the first position of the input val, where the first position is 0.

It returns -1 if the input val does not exist in the array.

If one of the arguments is MISSING, it returns MISSING.

If either of the arguments are non-array values, it returns NULL.

Example 17: Find which position "Brian Kilback" is in the public_likes array.

SELECT ARRAY_POSITION(t.public_likes, "Brian Kilback") AS array_position
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;
[
  {
    "array_position": 4
  }
]

ARRAY_PREPEND(val1, val2, … , expr)

Description

This function returns the new array after prepending the array expr with the specified val or multiple val arguments.

It requires a minimum of two arguments.

Arguments
val1, val2, …

[At least 1 is Required] The value or multiple value arguments to prepend to the input expr.

expression

[Required] The array you want to have the input value argument(s) prepended to.

Return Values

A new array with the input val argument(s) prepended to the input array expr.

If one of the arguments is MISSING, it returns MISSING.

If the last argument is a non-array, it returns NULL.

Example 18: Prepend "Dave Smith" to the front of the public_likes array.

SELECT ARRAY_PREPEND("Dave Smith",t.public_likes) AS prepend_val
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "prepend_val": [
      "Dave Smith",
      "Julius Tromp I",
      "Corrine Hilll",
      "Jaeden McKenzie",
      "Vallie Ryan",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow"
    ]
  }
]

ARRAY_PUT(expr, val1, val2, …)

Description

This function returns a new array with val or multiple val arguments appended if the val is not already present. Otherwise, it returns the unmodified input array expr.

It requires a minimum of two arguments.

Arguments
expr

[Required] The array you want to append the input value or value arguments.

val1, val2, …

[At least 1 is Required] The value or multiple value arguments that you want appended to the end of the input array expression.

Return Values

A new array with val or multiple val arguments appended if the val is not already present. Otherwise, it returns the unmodified input array expr.

If one of the arguments is MISSING, then it returns MISSING.

If the first argument is a non-array, then it returns NULL.

Example 19: Append "Dave Smith" to the end of the public_likes array.

SELECT ARRAY_PUT(t.public_likes, "Dave Smith") AS array_put
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "array_put": [
      "Julius Tromp I",
      "Corrine Hilll",
      "Jaeden McKenzie",
      "Vallie Ryan",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow",
      "Dave Smith"
    ]
  }
]

ARRAY_RANGE(start_num, end_num step_num ])

Description

This function returns a new array of numbers, from start_num until the largest number less than end_num. Successive numbers are incremented by step_int.

If step_int is not specified, then the default value is 1. If step_num is negative, then he function decrements until the smallest number greater than end_num.

Arguments
start_num

[Required] The integer to start a new array with.

end_num

[Required] The integer that is one number larger than the final integer in the output array.

step_num

[Optional; default is 1] The number between each array element.

If step_num is negative, then the function decrements until the smallest number greater than end_num.

Output Values

A new array of numbers, from start_num until the largest number less than end_num.

If any of the arguments are MISSING, then it returns MISSING.

If any of the arguments do not start with a digit, then it returns an error.

Example 20a: Make an array from 0 to 20 by stepping every 5th number.

SELECT ARRAY_RANGE(0, 25, 5) AS gen_array_range_5;

Results:
[
  {
    "gen_array_range_5": [
      0,
      5,
      10,
      15,
      20
    ]
  }
]

Example 20b: Make an array from 0.1 to 1.1 by stepping every 2nd number.

SELECT ARRAY_RANGE(0.1, 2) AS gen_array_range_2;

Results:
[
  {
    "gen_array_range_2": [
      0.1,
      1.1
    ]
  }
]

Example 20c: Make an array from 10 to 3 by stepping down every 3rd number.

SELECT ARRAY_RANGE(10, 3, -3) AS gen_array_range_minus3;

Results:
[
  {
    "gen_array_range-3": [
      10,
      7,
      4
    ]
  }
]

ARRAY_REMOVE(expr, val1, val2, …)

Description

This function returns a new array with all occurrences of the specified value or multiple value fields removed from the array expressionand it requires a minimum of two arguments.

Arguments
expr

[Required] The input array to have the specified val or multiple val fields removed.

val1, val2, …

[At least 1 is Required] The input value or multiple values to remove from the input array expr.

Output Values

A new array with all occurrences of the specified val or multiple val fields removed from the array expr.

If any of the arguments are MISSING, then it returns MISSING.

If the first argument is not an array, then it returns NULL.

Example 21: Remove "Vallie Ryan" from the public_likes array.

SELECT ARRAY_REMOVE(t.public_likes, "Vallie Ryan") AS remove_val
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "remove_val": [
      "Julius Tromp I",
      "Corrine Hilll",
      "Jaeden McKenzie",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow"
    ]
  }
]

ARRAY_REPEAT(val, rep_int)

Description

This function returns a new array with the specified val repeated rep_int times.

Arguments
val

[Required] The input value you want repeated.

rep_int

[Required] The integer number of times you want the input val repeated.

Output Values

A new array with the specified val repeated rep_int times.

If any of the arguments are MISSING, then it returns MISSING.

If the rep_int argument is not an integer, then it returns NULL.

Example 22: Make an array with "Vallie Ryan" three times.

SELECT ARRAY_REPEAT("Vallie Ryan", 3) AS repeat_val;

Results:
[
  {
    "repeat_val": [
      "Vallie Ryan",
      "Vallie Ryan",
      "Vallie Ryan"
    ]
  }
]

ARRAY_REPLACE(expr, val1, val2 max_int ])

Description

This function returns a new array with all occurrences of value1 replaced with value2.

If max_int is specified, than no more than max_int replacements will be performed.

Arguments
expr

[Required] The input array you want to replace val1 with val2.

val1

[Required] The existing value in the input expr you want to replace.

val2

[Required] The new value you want to take the place of val1 in the input expr.

max_int

[Optional. Default is no maximum] The number of maximum replacements to perform.

Return Values

A new array with all or max_int occurrences of val1 replaced with val2.

If any of the arguments are MISSING, then it returns MISSING.

If the first argument is not an array or if the second argument is NULL, then it returns NULL.

Example 23: Replace all occurrences of "Vallie Ryan" with "Valerie Ryan".

SELECT ARRAY_REPLACE(t.public_likes, "Vallie Ryan", "Valerie Ryan") AS replace_val
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "replace_val": [
      "Julius Tromp I",
      "Corrine Hilll",
      "Jaeden McKenzie",
      "Valerie Ryan",
      "Brian Kilback",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Elnora Trantow"
    ]
  }
]

ARRAY_REVERSE(expr)

Description

This function returns a new array with all the elements of expr in reverse order.

Arguments
expr

[Required] The input array whose elements you want to reverse.

Return Values

A new array with all the elements of expr in reverse order.

If the argument is MISSING, then it returns MISSING.

If the argument is a non-array value, then it returns NULL.

Example 24: Reverse the values in the public_likes array.

SELECT ARRAY_REVERSE(t.public_likes) AS reverse_val
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "reverse_val": [
      "Elnora Trantow",
      "Ms. Moses Feeney",
      "Lilian McLaughlin",
      "Brian Kilback",
      "Vallie Ryan",
      "Jaeden McKenzie",
      "Corrine Hilll",
      "Julius Tromp I"
    ]
  }
]

ARRAY_SORT(expr)

Description

This function returns a new array with the elements of expr sorted in N1QL collation order.

Arguments
expr

[Required] The input array you want sorted.

Return Values

A new array with the elements of expr sorted in N1QL collation order.

If the argument is MISSING, then it returns MISSING.

If the argument is a non-array value, then it returns NULL.

Example 25: Sort the public_likes array.

SELECT ARRAY_SORT(t.public_likes) AS sorted_array
FROM `travel-sample` t
WHERE type="hotel"
LIMIT 1;

Results:
[
  {
    "sorted_array": [
      "Brian Kilback",
      "Corrine Hilll",
      "Elnora Trantow",
      "Jaeden McKenzie",
      "Julius Tromp I",
      "Lilian McLaughlin",
      "Ms. Moses Feeney",
      "Vallie Ryan"
    ]
  }
]

ARRAY_STAR(expr)

Description

This function converts an array of expr objects into an object of arrays.

Arguments
expr

[Required] The input array you want to convert into an object of arrays.

Output Values

An object of arrays.

If the argument is MISSING, then it returns MISSING.

If the argument is a non-array value, then it returns NULL.

Example 26: Convert a given array of two documents each with five items into an object of five arrays each with two documents.

SELECT ARRAY_STAR( [
   {
    "address": "Capstone Road, ME7 3JE",
    "city": "Medway",
    "country": "United Kingdom",
    "name": "Medway Youth Hostel",
    "url": "http://www.yha.org.uk"
  },
  {
    "address": "6 rue aux Juifs",
    "city": "Giverny",
    "country": "France",
    "name": "The Robins",
    "url": "http://givernyguesthouse.com/robin.htm"
  }]) AS array_star;

Results:
[
  {
    "array_star": {
      "address": [
        "Capstone Road, ME7 3JE",
        "6 rue aux Juifs"
      ],
      "city": [
        "Medway",
        "Giverny"
      ],
      "country": [
        "United Kingdom",
        "France"
      ],
      "name": [
        "Medway Youth Hostel",
        "The Robins"
      ],
      "url": [
        "http://www.yha.org.uk",
        "http://givernyguesthouse.com/robin.htm"
      ]
    }
  }
]

Array references ( doc.f[].id )*

You can use an asterisk (*) as an array subscript which converts the array to an object of arrays. The following example returns an array of the ages of the given contact’s children:

SELECT children[*].age FROM contacts WHERE fname = "Dave"

An equivalent query can be written using the array_star() function:

SELECT array_star(children).age FROM contacts WHERE fname = "Dave"

ARRAY_SUM(expr)

Description

This function returns the sum of all the non-NULL number values in the expr array.

Arguments
expr

[Required] The input array of numbers you want to know the total value of.

Return Values

The sum of all the non-NULL number values in the expr array.

If there are no number values, then it returns 0 (zero).

If the argument is MISSING, then it returns MISSING.

If the argument is a non-array value, then it returns NULL.

Example 27: Find the total of a given array of numbers.

SELECT ARRAY_SUM([0,1,1,2,3,5]) as sum;

Results:
[
  {
    "sum": 12
  }
]

ARRAY_SYMDIFF(expr1, expr2, …)

Synonym: ARRAY_SYMDIFF1(expression1, expression2, …)

Description

This function returns a new array based on the set symmetric difference, or disjunctive union, of the input expression arrays. The new array contains only those elements that appear in exactly one of the input arrays, and it requires a minimum of two arguments.

Arguments
expr1, expr2, …

[At least 2 are Required] The input arrays to compare.

Return Values

A new array containing only those elements that appear in exactly one of the input arrays.

If any of the arguments is MISSING, then it returns MISSING.

If any of the arguments is a non-array value, then it returns NULL.

The difference between ARRAY_SYMDIFF() and ARRAY_SYMDIFFN() is that the former function includes the value when it appears only once while the latter function includes the value when it appears odd number of times in the input arrays.
Refer to the following article for more information on the difference between a normal and n-ary symdiff: https://en.wikipedia.org/wiki/Symmetric_difference.

Example 28: Find the elements that appear in exactly one of these three input arrays.

SELECT ARRAY_SYMDIFF([1, 2], [1, 2, 4], [1, 3]) AS symm_diff1;

Results:
[
  {
    "symm_diff1": [
      3,
      4
    ]
  }
]

ARRAY_SYMDIFFN(expr1, expr2, …)

Description

This function returns a new array based on the set symmetric difference, or disjunctive union, of the input arrays. The new array contains only those elements that appear in an odd number of input arrays, and it requires a minimum of two arguments.

Arguments
expr1, expr2, …

[At least 2 are Required] The input arrays to compare.

Return Values

A new array containing only those elements that appear in an odd number of the input arrays.

If any of the arguments is MISSING, then it returns MISSING.

If any of the arguments is a non-array value, then it returns NULL.

The difference between ARRAY_SYMDIFF() and ARRAY_SYMDIFFN() is that the former function includes the value when it appears only once while the latter function includes the value when it appears odd number of times in the input arrays.
Refer to the following article for more information on the difference between a normal and n-ary symdiff: https://en.wikipedia.org/wiki/Symmetric_difference.

Example 29: Find the elements that appear in an odd number of these three input arrays.

SELECT ARRAY_SYMDIFFN([1, 2], [1, 2, 4], [1, 3]) AS symm_diffn;

Results:
[
  {
    "symm_diffn": [
      1,
      3,
      4
    ]
  }
]

ARRAY_UNION(expr1, expr2, …)

Description

This function returns a new array with the set union of the input arrays, and it requires a minimum of two arguments.

Arguments
expr1, expr2, …

[At least 2 are Required] The input arrays to compare.

Return Values

A new array with the set union of the input arrays.

If any of the arguments is MISSING, then it returns MISSING.

If any of the arguments is a non-array value, then it returns NULL.

Example 30a: List the union of three given arrays.

SELECT ARRAY_UNION([1, 2], [1, 2, 4], [1, 3]) AS array_union;

Results:
[
  {
    "array_union": [
      3,
      2,
      1,
      4
    ]
  }
]

Example 30b: List the union of two given arrays with a string.

SELECT ARRAY_UNION([1, 2], [1, 2, 4], "abc") AS array_union;

Results:
[
  {
    "array_union": null
  }
]