Remove array values in pgSQL

Question

Is there a way to remove a value from an array in pgSQL? Or to be more precise, to pop the last value? Judging by this list the answer seems to be no. I can get the result I wan

Answer 1

There IS a SIMPLE way to remove a value from an array in PLAIN SQL:

SELECT unnest('{5,NULL,6}'::INT[]) EXCEPT SELECT NULL

it will remove all NULL values from array. Result will be:

#| integer |
------------
1|    5    |
2|    6    |

Answer 2

I'm running on 9.2 and I'm able to execute this:

update tablename set arrcolumn=arrcolumn[1:array_length(arrcolumn)-1];

or you can shift off the front element with the same kind of thing:

update tablename set arrcolumn=arrcolumn[2:array_length(arrcolumn)];

Careful, programmers -- for some reason still unknown to science, pgsql arrays are 1-indexed instead of 0-indexed.

Answer 3

In version 9.3 and above you can do:

update users set flags = array_remove(flags, 'active')

Answer 4

I've created a array_pop function so you can remove an element with known value from an array.

CREATE OR REPLACE FUNCTION array_pop(a anyarray, element character varying)
RETURNS anyarray
LANGUAGE plpgsql
AS $function$
DECLARE 
    result a%TYPE;
BEGIN
SELECT ARRAY(
    SELECT b.e FROM (SELECT unnest(a)) AS b(e) WHERE b.e <> element) INTO result;
RETURN result;
END;
$function$ 

there is also a gist version https://gist.github.com/1392734

Answer 5

The simplest way to remove last value:

array1 = array[1,2,3]
array1 = ( select array1[1:array_upper(array1, 1) - 1] )

Answer 6

No, I don't think you can. At least not without writing something ugly like:

SELECT ARRAY (
 SELECT UNNEST(yourarray) LIMIT (
  SELECT array_upper(yourarray, 1) - 1
 )
)