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CONCAT, || ​

Concatenate a series of strings.

CONCAT(string [, string [ , … ] ])

You can also use the || operator to concatenate a series of strings. CONCAT and || also accept values that are not character strings, such as integers and timestamps.

The CONCAT function and the || operator have exactly the same behavior.

Trailing spaces in CHAR strings are ignored (trimmed) when they are concatenated. Trailing spaces in VARCHAR strings are preserved.

Examples ​

The following example concatenates four strings (two VARCHAR columns (name and nickname) and two literal values).

premdb=# SELECT CONCAT(name,', The ',nickname) AS names 
FROM team LIMIT 5;
            names              
--------------------------------
 Arsenal, The Gunners
 Aston Villa, The Villains
 Birmingham City, The Blues
 Blackpool, The Seasiders
 Bolton Wanderers, The Trotters
(5 rows)

The following example concatenates three character columns:

premdb=# SELECT name||nickname||city AS names FROM team LIMIT 5;
            names              
--------------------------------
 ArsenalGunnersLondon
 Aston VillaVillainsBirmingham
 Birmingham CityBluesBirmingham
 BlackpoolSeasidersBlackpool
 Bolton WanderersTrottersBolton
(5 rows)

The following example concatenates two SMALLINT columns and a colon character:

premdb=# select concat(htid,':',atid) from team order by htid;
 concat 
--------
 2:51
 3:52
 4:53
 5:54
 6:55
 7:56
...

Compare the results of concatenated strings with trailing spaces in CHAR and VARCHAR expressions:

premdb=> select 'abc '::char(5) || 'zzz '::char(5) as concat_char, length(concat_char) from sys.const;
 concat_char | length 
-------------+--------
 abczzz      |      6
(1 row)

premdb=> select 'abc '::varchar(5) || 'zzz '::varchar(5) as concat_varchar, length(concat_varchar) from sys.const;
 concat_varchar | length 
----------------+--------
 abc zzz        |      8
(1 row)