How the CONCAT() Function Works in PostgreSQL

In PostgreSQL, the CONCAT() function concatenates the text representations of its arguments.

Syntax

The syntax goes like this:

concat ( val1 "any" [, val2 "any" [, ...] ] )

Example

Here’s an example to demonstrate:

SELECT CONCAT('Squid', 'Game');

Result:

SquidGame

If we wanted a space between the strings, we can either include a space in one of the strings, or include a space as a separate argument:

SELECT 
    CONCAT('Squid ', 'Game') AS "Option 1",
    CONCAT('Squid', ' ', 'Game') AS "Option 2";

Result:

  Option 1  |  Option 2  
------------+------------
 Squid Game | Squid Game

Alternatively, we could use the CONCAT_WS() function, with a space as the first argument.

Concatenating Numbers

PostgreSQL concatenates the text representation of its arguments, so we can concatenate numbers without having to explicitly convert them to a string:

SELECT CONCAT(4, 56);

Result:

Although, be careful if there are leading zeros:

SELECT CONCAT(001, 456);

Result:

Null Arguments

Null arguments are ignored:

SELECT CONCAT('Player ', NULL, 456);

Result:

Player 456

No Arguments

Calling CONCAT() without passing any arguments results in an error:

SELECT CONCAT();

Result:

ERROR:  function concat() does not exist
LINE 1: SELECT CONCAT();
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.