主题：请教：怎样用SELECT CASE 写这段代码

请教：怎样用SELECT CASE 写这段代码

If e.IsFocusCell Then   
    If e.Col.Name = "产品名称" And e.Row.IsNull("订单号") = True Then
        e.Cancel = True
    ElseIf e.Col.Name = "订购件数" And e.Row.IsNull("产品名称") = True Then
        e.Cancel = True
    ElseIf  e.Col.Name = "到货日期" And e.Row.IsNull("订购件数") = True Then
        e.Cancel = True
    Else
    End If
End If

Select Case e.Col.Name

     Case  "产品名称"

               if e.Row.IsNull("订单号") = True then

                  e.Cancel = True
               end if

 Case  "订购件数"

               if e.Row.IsNull("产品名称") = True then

                  e.Cancel = True
               end if

 Case  "到货日期"

               if e.Row.IsNull("订购件数") = True then

                  e.Cancel = True
               end if

end select