string_agg()

Concatenates the non-null input values into a string. Each value after the first is preceded by the corresponding delimiter (if it's not null).

Signature

string_agg ( value text, delimiter text ) → text
string_agg ( value bytea, delimiter bytea ORDER BY input_sort_columns ) → bytea

Examples

SELECT string_agg(product, ', ' ORDER BY product) FROM orders;

                     string_agg                     
----------------------------------------------------
 cable, keyboard, keyboard, monitor, monitor, mouse
(1 row)

Run against PostgreSQL 18.6 on 2026-09-13. This is the output we got, not the documentation’s.

In other engines

PostgreSQL	string_agg
MySQL	GROUP_CONCAT(x SEPARATOR ', ')
SQL Server	STRING_AGG(x, ', ')
Oracle	LISTAGG(x, ', ') WITHIN GROUP (ORDER BY x)
SQLite	group_concat(x, ', ')

MySQL silently truncates at group_concat_max_len, 1024 bytes by default — the query succeeds and the answer is short. Oracle requires the WITHIN GROUP ordering clause; PostgreSQL and SQL Server take ORDER BY inside the call and are happy without it.

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