protected void btLuuCt_Click(object sender, EventArgs e)
        {
            int               ma    = int.Parse(lbMadh.Text);
            DAO_Entity        daokh = new DAO_Entity();
            DTODonDatHang     dtodh = new DTODonDatHang();
            DTOChiTietDonHang dtoct = daokh.LayTongTien(ma);

            dtodh.TongTien = int.Parse(dtoct.ThanhTien.ToString());
            dtodh.CongNoDH = dtodh.TongTien;
            daokh.CapNhatTongTien(dtodh);

            Response.Redirect("~/QLBoPhan_TiepXucKH/TaoDonHang.aspx?MaKH=" + lbMaKH.Text);
        }