参考代码
Select Case e.DataCol.name
Case "产品编号","调账数量"
Dim d As Date = Date.Today
d = d.AddDays(-1)
d = new Date(d.Year, d.Month, 1)
Dim sum1 As Double = DataTables("入库表").Compute("sum(入库数量)", "产品编号 = '" & e.DataRow("产品编号") & "' and 入库日期 >= #" & d & "# and 入库日期 < #" & d.AddMonths(1) & "#")
Dim sum2 As Double = DataTables("出库表").Compute("sum(出库数量)", "产品编号 = '" & e.DataRow("产品编号") & "' and 出库日期 >= #" & d & "# and 出库日期 < #" & d.AddMonths(1) & "#")
e.DataRow("上月总出库") = sum2
e.DataRow("上月总入库") = sum1
End Select