Ok, habs über eine Funtion gelöst:
CREATE OR REPLACE FUNCTION f_usr_groups (int) RETURNS text AS $$
DECLARE
groups text;
r_groups RECORD;
BEGIN
groups = '';
FOR r_groups IN SELECT usr_group_group_id FROM tbl_usr_group WHERE usr_group_usr_id = $1 ORDER BY usr_group_group_id LOOP
groups := groups || ',' || r_groups.usr_group_group_id;
END LOOP;
groups := trim (leading ',' from groups);
RETURN groups;
END;
$$ LANGUAGE 'plpgsql';
Siehe da, liefert genau das, was ich brauche :)
Dane fürs Nachdenken :)