Contents
array_prepend()
A function for prepending to an array
array_prepend() is a is a system function for prepending an element to the front of an array.
array_prepend() was added in PostgreSQL 7.4.
Usage
array_prepend (anyelement,anyarray) →anyarray
Change history
- PostgreSQL 7.4
- added (commit 730840c9)
Examples
Basic usage examples for array_prepend():
postgres=# SELECT array_prepend(1, ARRAY[2,3]);
array_prepend
---------------
{1,2,3}
(1 row)
postgres=# SELECT array_prepend('foo', ARRAY['bar','baz']);
array_prepend
---------------
{foo,bar,baz}
(1 row)
Note that the anyelement || anyarray operator is equivalent:
postgres=# SELECT 1 || ARRAY[2,3];
?column?
----------
{1,2,3}
(1 row)
It is not possible to prepend arbitrary data types to an array of a particular type:
postgres=# SELECT array_prepend(1, ARRAY['bar','baz']);
ERROR: function array_prepend(integer, text[]) does not exist
LINE 1: SELECT array_prepend(1, ARRAY['bar','baz']);
^
HINT: No function matches the given name and argument types. You might need to add explicit type casts
References
- PostgreSQL documentation: Array Functions