Hi,
Try this query to know link between ORPC and ORPD tables.
SELECT T0.[DocNum], T0.[DocDate], T0.[CardCode], T0.[CardName], T3.[DocNum], T3.[DocDate]
FROM
ORPD T0 INNER JOIN RPD1 T1 ON T0.DocEntry = T1.DocEntry left join RPC1 T2 on T2.[BaseEntry] = T1.[DocEntry] and T2.[BaseLine] = T1.[LineNum] INNER JOIN ORPC T3 ON T2.DocEntry = T3.DocEntry
Thanks & Regards,
Nagarajan