So I'm using a fairly complex query with a couple of sub-queries as expressions:
SELECT tblPPIn.BatchID,
tblPPIn.Qty AS [Qty In],
IIf(IsNull((SELECT Sum(tblPPProcessed.QtyProcessed) AS SumOfQty1 FROM tblPPProcessed WHERE (((tblPPProcessed.BatchID)=(tblPPIn.BatchID)));)),'0',(SELECT...