将下面的代码设置在DataColChanged事件:
Select Case e.DataCol.Name
Case "入库日期","出库日期"
Dim dr As DataRow = e.DataRow
If dr.IsNull("入库日期") OrElse dr.IsNull("出库日期") Then
dr("库存时长") = Nothing
Else
Dim tp As TimeSpan = dr("出库日期") - dr("入库日期")
dr("库存时长") = tp.TotalDays
End If
End Select
参考这里的示例三:
http://www.foxtable.com/help/topics/1452.htm