主题：表达式生成的问题

Select case

    Case "身份证号码"
        If e.NewValue Is Nothing Then
            Return
        Else
            Dim dt As Date = ReadBirthday(e.NewValue)

            Dim td As Date = Date.Today

            Dim n As Integer = td.Year - dt.Year
            If dt.AddMonths(n*12) > td Then
                n = n - 1
            End If

            e.DataRow("出生日期") = dt
            e.DataRow("年龄") = n
        End If

End select