public static int ThanhToan(string thongTinKhachHang, List <SAN_PHAM> imei)
        {
            List <SAN_PHAM> xacThuc  = new List <SAN_PHAM>();
            int             tongCong = SanPham.LayTongCong(imei);
            HOA_DON         hd       = TaoPhieuXuat(thongTinKhachHang);

            hd.TONG_CONG = tongCong;
            int maHoaDon = HOA_DON.insert(hd);

            for (int i = 0; i < imei.Count; i++)
            {
                SAN_PHAM sp = KhoHang.XuatKho(imei[i]);
                ChiTietHoaDon.XuatHang(maHoaDon, sp);
            }
            return(maHoaDon);
        }
 public static bool NhanBaoHanh(int maHoaDon)
 {
     SanPham.NhanBaoHanh(ChiTietHoaDon.LayChiTietHoaDon(maHoaDon)[0].IMEI);
     return(true);
 }