PostgreSQL 18 reference · String Functions

PostgreSQL CONCAT_WS() Function

Join values with a separator between them, skipping NULLs. The first argument is the separator.

PostgreSQL 18 Since 9.1

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Syntax

concat_ws(sep, val1, val2, ...)

Parameter	Description
`sep`	The separator.
`val`	The values to join.

Text, or NULL if sep is NULL.

Join with a separator

SELECT concat_ws(', ', name, city, country) AS address
FROM customers
WHERE customer_id IN (1, 7);

Output

         address
--------------------------
 Ada Lovelace, London, UK
 Barbara Liskov, USA
(2 rows)

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Numbers too

SELECT concat_ws('/', 2026, 3, 9) AS path;

Output

   path
----------
 2026/3/9
(1 row)

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Version	Change
PostgreSQL 9.1	Added

CONCAT() · Join any number of values into one string, treating NULL arguments as empty strings.
STRING_AGG() · Join a group's non-NULL values into one string with a separator, optionally in a given ORDER BY order.
SQL String Functions · tutorial