Remove array values in pgSQL

Is there a way to remove a value from 开发者_StackOverflow中文版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 want with an additional index pointer, but it's a bit cumbersome.

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In version 9.3 and above you can do:

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

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The simplest way to remove last value:

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

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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
 )
)

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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    |

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I'm not sure about your context, but this should give you something to work with:

CREATE TABLE test (x INT[]);
INSERT INTO test VALUES ('{1,2,3,4,5}');

SELECT x AS array_pre_pop,
       x[array_lower(x,1) : array_upper(x,1)-1] AS array_post_pop, 
       x[array_upper(x,1)] AS popped_value 
FROM test;


 array_pre_pop | array_post_pop | popped_value 
---------------+----------------+--------------
 {1,2,3,4,5}   | {1,2,3,4}      |            5

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Here is a function I use for integer[] arrays

CREATE OR REPLACE FUNCTION array_remove_item (array_in INTEGER[], item INTEGER)
RETURNS INTEGER[]
LANGUAGE SQL
AS $$
SELECT ARRAY(
  SELECT DISTINCT $1[s.i] AS "foo"
    FROM GENERATE_SERIES(ARRAY_LOWER($1,1), ARRAY_UPPER($1,1)) AS s(i)
   WHERE $2 != $1[s.i]
   ORDER BY foo
);
$$;

This is obviously for integer arrays but could be modified for ANYARRAY ANYELEMENT

=> select array_remove_item(array[1,2,3,4,5], 3);
-[ RECORD 1 ]-----+----------
array_remove_item | {1,2,4,5}

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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.

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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

---

Try this:

update table_name set column_name=column_name[1:array_upper(column_name, 1)-1];

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My function for all types of arrays.

Outer function:

CREATE OR REPLACE FUNCTION "outer_array"(anyarray, anyarray) RETURNS anyarray AS $$
    SELECT
        "new"."item"
    FROM (
        SELECT
            ARRAY(
                SELECT
                    "arr"."value"
                FROM (
                    SELECT
                        generate_series(1, array_length($1, 1)) AS "i",
                        unnest($1)                              AS "value"
                ) "arr"
                WHERE
                    "arr"."value" <> ALL ($2)
                ORDER BY
                    "arr"."i"
            ) AS "item"
    ) "new"
    $$
LANGUAGE sql
IMMUTABLE
RETURNS NULL ON NULL INPUT
;

Inner function:

CREATE OR REPLACE FUNCTION "inner_array"(anyarray, anyarray) RETURNS anyarray AS $$
    SELECT
        "new"."item"
    FROM (
        SELECT
            ARRAY(
                SELECT
                    "arr"."value"
                FROM (
                    SELECT
                        generate_series(1, array_length($1, 1)) AS "i",
                        unnest($1)                              AS "value"
                ) "arr"
                WHERE
                    "arr"."value" = ANY ($2)
                ORDER BY
                    "arr"."i"
            ) AS "item"
    ) "new"
$$
LANGUAGE sql
IMMUTABLE
RETURNS NULL ON NULL INPUT
;