SQL Procedure

CREATE DEFINER=`root`@`%` PROCEDURE `p6`()
BEGIN
DECLARE z, anzahl, wert, summe INTEGER DEFAULT 0;
  SELECT COUNT(bestellnummer) INTO anzahl FROM bestellung;
  schleife: LOOP
  SET z=z+1;
  SELECT bestellsumme INTO wert FROM bestellung WHERE bestellnummer = z;
  SET summe=wert+summe;
    IF z = anzahl THEN LEAVE schleife;
END IF;
END LOOP;
SELECT summe;
END