Is fkstoreId and storeid the same thing? I am assuming that it is, because if that were not the case, the query could fail if the subquery returns more than one value.  You might also try this:SELECT t.checknumber,       t.FKStoreID,       t.Dateofbusiness,       SUM(t.amount)FROM   HstGndTender t	   LEFT JOIN dpvhstchecksummary s ON		s.storeId = t.StoreId		AND s.dateofbusiness = t.Dateofbusiness		AND s.checkid = t.checknumberWHERE  t.storeID = 123       AND t.dateofbusiness = '2012-09-05'       AND t.[type] = 1GROUP BY       t.checknumber,       t.dateofbusiness,       t.fkstoreIdHAVING       SUM(t.amount) <> SUM(s.NetSales + s.Tax)