Crystal Report previous() Function

 sometimes we may need to check the duplicate record based on our  query . 

let's you have scenario  PO Number :1  have 2 GRPO which repeat the PO Qty  in another line of GRPO 2.

 to get rid of this we can use  Previous() Function in crystal report .

----------------------------------- Formula -----------------

if not onfirstrecord and {SP_PurchaseReport;1.POLineNum}=previous({SP_PurchaseReport;1.POLineNum}) and {SP_PurchaseReport;1.PODocEntry}=Previous({SP_PurchaseReport;1.PODocnry})

then 0

ELSE

{SP_PurchaseReport;1.Ordered Qty}

--------------------------formula ---------------------------------