PostgreSQL 18 reference · String Functions

PostgreSQL || Concatenation Operator

Join strings with the || operator. If either side is NULL the result is NULL; use concat() to skip NULLs instead.

PostgreSQL 18

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Syntax

string || string

Parameter	Description
`string`	Values to join; non-text values are converted when one side is text.

Text, or NULL.

Build a label

SELECT name || ' (' || country || ')' AS label
FROM customers
LIMIT 2;

Output

       label
-------------------
 Ada Lovelace (UK)
 Alan Turing (UK)
(2 rows)

Run this on your computer — see “Get Started” for setup.

NULL turns the result NULL

SELECT name || ', ' || city AS with_pipes, concat(name, ', ', city) AS with_concat
FROM customers
WHERE customer_id = 7;

Output

 with_pipes |   with_concat
------------+------------------
 NULL       | Barbara Liskov,
(1 row)

Run this on your computer — see “Get Started” for setup.

CONCAT() · Join any number of values into one string, treating NULL arguments as empty strings.
CONCAT_WS() · Join values with a separator between them, skipping NULLs. The first argument is the separator.
COALESCE() · Return the first argument that isn't NULL. The standard way to replace NULL with a default.
SQL String Functions · tutorial