SQL weitere Berechnungen mit Unterabfrage

[omata]

SQL-Code:

SELECT r.RECHNR, 
       SUM(v.VKPREIS) AS NETTO, 
       SUM(v.VKPREIS) * 0,15 AS NETTO15,
       SUM(v.VKPREIS) * 0,19 AS NETTO19
       SUM(v.EKPREIS) AS BRUTTO, 
       SUM(v.EKPREIS) * 0,15 AS BRUTTO15,
       SUM(v.VKPREIS) + SUM(v.EKPREIS) AS NETTOBRUTTO
FROM Rechnungen r
INNER JOIN VERKPOS v
  ON r.ID = v.IDRECHNUNG
GROUP BY r.RECHNR