e.DataRow("数量") = DataTables("订单").Compute("Sum(数量)","[产品] = '" & e.Datarow("产品") & "' And 客户 = '" & e.DataRow("客户") & “‘ And 雇员 = '" & e.Datarow("雇员") & ”’“)
参考:
http://www.foxtable.com/help/topics/1284.htm