SELECT Adr.Kdnr, Adr.Name1, Sum(Std.DauerReal) AS ZReal, Sum(Std.DauerAbrechnung) AS ZAbrechnung
FROM (Adr INNER JOIN Std ON Adr.Kdnr = Std.adrkdnr) INNER JOIN System_MA ON Std.Mitarbeiter = System_MA.id
GROUP BY Adr.Kdnr, Adr.Name1
order by Sum(STD.Dauerreal)