Postgres: Перебор строк в цикле

CREATE OR REPLACE FUNCTION core.fx_artist_del(integer, timestamp with time zone)
  RETURNS integer AS
$BODY$
--
-- Удаление исполнителя
--
DECLARE
    r core.artists_tracks%rowtype;
    k core.artists_clips%rowtype;
    save_artist_deleted timestamp;
BEGIN
    SELECT artist_deleted INTO save_artist_deleted
        FROM core.artists WHERE obj_id=$1;

    IF NOT save_artist_deleted IS NULL THEN
        RETURN 0;
    END IF;

    FOR r IN SELECT core.artists_tracks.* FROM core.artists_tracks
      INNER JOIN core.tracks ON at_track_id=core.tracks.obj_id
        WHERE track_deleted IS NULL AND at_artist_id=$1
    LOOP
       PERFORM core.fx_track_del(r.at_track_id,$2);
    END LOOP;

    UPDATE core.artists SET artist_deleted=$2 WHERE obj_id=$1;

    RETURN 1;

END
--
$BODY$
  LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER
  COST 100;
ALTER FUNCTION core.fx_artist_del(integer, timestamp with time zone) OWNER TO sk4_admin;
GRANT EXECUTE ON FUNCTION core.fx_artist_del(integer, timestamp with time zone) TO sk4_admin;
GRANT EXECUTE ON FUNCTION core.fx_artist_del(integer, timestamp with time zone) TO public;