销售订单表中有"客户姓名,客户电话,客户地址"三列,在DataColChanging事件中禁止"客户姓名,客户电话,客户地址"三列值同时相同,如在以下的代码中如何加入对"客户姓名,客户电话,客户地址"的同时判断?

Select Case e.DataCol.Name
    Case "客户姓名"

            Dim cmd As New SQLCommand
            Dim dt As DataTable
            Dim db As DataRow
            cmd.C 
            cmd.CommandText = "SELECT  客户姓名 From {销售订单}"
            dt = cmd.ExecuteReader()
            db = dt.Find("客户姓名 = \'" & trim(e.NewValue) & "\'")
            If db IsNot Nothing \'一定要判断是否存在对应的行
                e.Cancel =True
                Messagebox.Show("客户姓名重复,请重新录入!","提示",MessageBoxButtons.OK, MessageBoxIcon.Information)
            End If