ARRAY_JOIN

Joins the elements of an array into a single string using a specified delimiter.

Signatures

Returns: A single string with array elements joined by the delimiter

ARRAY_JOIN(array: ARRAY<T>, delimiter: VARCHAR, [null_replacement: VARCHAR]) → VARCHAR

sql

Parameter	Type	Required	Description
`array`	`ARRAY<T>`	Yes	Array of strings to join together
`delimiter`	`VARCHAR`	Yes	String to insert between array elements
`null_replacement`	`VARCHAR`	No	Optional replacement string for NULL values

Notes

Joins array elements into a single string using the specified delimiter
NULL values are omitted unless a replacement string is provided
Empty arrays return an empty string
Single element arrays return just that element (no delimiter)
Useful for creating CSV-like output or human-readable lists

Examples

FeatureQL

SELECT
    f1 := ARRAY_JOIN(ARRAY['A', 'B', 'C'], ', '),  -- Join with comma and space
    f2 := ARRAY_JOIN(ARRAY['apple', 'banana', 'cherry'], '|'),  -- Join with pipe delimiter
    f3 := ARRAY_JOIN(ARRAY['hello', 'world'], ''),  -- Join with no delimiter
    f4 := ARRAY_JOIN(ARRAY['one'], ','),  -- Single element array
    f5 := ARRAY_JOIN(ARRAY[]::VARCHAR[], ','),  -- Empty array returns empty string
    f6 := ARRAY_JOIN(ARRAY['A', NULL::VARCHAR, 'C'], ','),  -- NULL becomes empty string
    f7 := ARRAY_JOIN(ARRAY['A', NULL::VARCHAR, 'C'], ',', 'empty')  -- NULL replacement
;

Result

f1 VARCHAR	f2 VARCHAR	f3 VARCHAR	f4 VARCHAR	f5 VARCHAR	f6 VARCHAR	f7 VARCHAR
A, B, C	apple\|banana\|cherry	helloworld	one	(empty)	A,C	A,empty,C

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Last update at: 2026/03/03 16:47:38

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