But when I use it as a function it always returns false:
CREATE OR REPLACE FUNCTION grpl_collection.copy_in_collection_name(cpid bigint, colname text)
RETURNS boolean
LANGUAGE plpgsql
AS $function$
BEGIN
RETURN cpid in (select copy from grpl_collection.collections_copy_map where copy=cpid and collection in
(WITH RECURSIVE
q AS
(
SELECT c.id
FROM grpl_collection.collections c
WHERE name=$$colname$$ <<<------------
UNION
SELECT cn.id
FROM q
JOIN grpl_collection.collections cn
ON cn.parent = q.id
)
SELECT id FROM q ));
END;
$function$
$$colname$$ is a string whose contents is the literal 'colname', not the function argument named colname as you seem to want.
David J.
