Hi,
Try this:
SELECT T0.[CardCode], T0.[CardName], T0.[DocNum],sum(T1.[Quantity]) FROM ORDR T0 INNER JOIN RDR1 T1 ON T0.DocEntry = T1.DocEntry WHERE T1.[PickIdNo] is null and T0.[DocStatus] = 'o' GROUP BY T0.[CardCode], T0.[CardName], T0.[DocNum]
Thanks & Regards,
Nagarajan