I am very new to ampscripting and I have inherited an ampscript for pulling promo code that was written by the previously developer that I couldn't make sense of. Here's the ampscript in question:
%%[var @em, @couponCode, @existingRow, @row, @couponDE set @em = AttributeValue("Email") set @existingRow = LookupRows("PromocodeDE","EmailAddress",@em) if rowcount(@existingRow) > 0 then set @row = Row(@existingRow,1) set @couponCode = field(@row,"CouponCode") else if _messagecontext == "PREVIEW" then set @couponCode = "XX TEST XX" else set @couponCode = ClaimRowValue("PromocodeDE", "CouponCode", "IsIssued","None Available","DateIssued",NOW(),"JobID",jobid,"ListID",ListID,"BatchID",_JobSubscriberBatchID,"SubscriberKey",_subscriberKey,"SubscriberID", SubscriberID,"EmailAddress",@em,"EmailName",emailname_) endif endif ]%% %%=v(@couponCode)=%%
I understand that ClaimRowValue should suffice for pulling of the promo codes and displaying it in the EDM. But I don't understand why there is a check before that to search the email address in the promo code DE.
Is this a common practice and what purpose does it serve?