Private Sub gysmc_BeforeUpdate(Cancel As Integer)
    If DCount("*", "tblcode_gys", "gysmc='" & Me.gysmc & "' and gysid <>'" & Me.gysID & "'") > 0 Then
        MsgBox "你输入的数据已经存在，请重新输入!", vbCritical, "警告"
        Cancel = True
        Me!gysmc.Undo
        Exit Sub
    End If
End Sub