On Wed, Oct 17, 2007 at 10:19:43AM -0500, Josh Trutwin wrote:
> Hi,
>
> Is it possible to find the intersection of two array values?
>
> a = '{1,2,3}'
> b = '{2,3,4}'
>
> a intersect b = '{2,3}'
>
> Assume I need to write a pl/pgsql function to do this.
You can use an SQL function, which has the advantage of always being
available :)
It's up to you to ensure that the input arrays have the same type.
Cheers,
David.
CREATE OR REPLACE FUNCTION array_intersect(ANYARRAY, ANYARRAY)
RETURNS ANYARRAY
LANGUAGE SQL
AS $$
SELECT ARRAY(
SELECT $1[i] AS "the_intersection"
FROM generate_series(
array_lower($1,1),
array_upper($1,1)
) AS i
INTERSECT
SELECT $2[j] AS "the_intersection"
FROM generate_series(
array_lower($2,1),
array_upper($2,1)
) AS j
);
$$;
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