public bool Save(HoaDonNhapHang hd)
        {
            this.connect();
            bool   bCheck = true;
            string query  = "insert into HoaDonNhapHang([id],[idNguoiLap],[NgayLap],[TongGiaTien])"
                            + "values(@ID,@IDuser,@date,@tong)";

            this.cm = new SqlCommand(query, cnn);
            this.cm.Parameters.AddWithValue("ID", hd.ID.Trim());
            this.cm.Parameters.AddWithValue("IDuser", hd.IDNguoiLap.Trim());
            this.cm.Parameters.AddWithValue("date", hd.NgayLap.ToString("yyyy-MM-dd"));
            this.cm.Parameters.AddWithValue("tong", hd.TongTien);
            try
            {
                this.cm.ExecuteNonQuery();
                this.disconnect();
            }
            catch (Exception ex)
            {
                this.disconnect();
                bCheck = false;
                throw ex;
            }
            return(bCheck);
        }
        public bool Update(HoaDonNhapHang hd)
        {
            this.connect();
            bool   bCheck = true;
            string query  = "update HoaDonNhapHang set [NgayLap]=@date, [TongGiaTien]=@tong" +
                            " where [id] = @ID";

            this.cm = new SqlCommand(query, cnn);
            this.cm.Parameters.AddWithValue("ID", hd.ID.Trim());
            this.cm.Parameters.AddWithValue("date", hd.NgayLap.ToString("yyyy-MM-dd"));
            this.cm.Parameters.AddWithValue("tong", hd.TongTien);
            try
            { this.cm.ExecuteNonQuery(); this.disconnect(); }
            catch (Exception ex) { this.disconnect(); bCheck = false; throw ex; }
            return(bCheck);
        }
        public bool update(string idHD, string idNguoiLap, DateTime ngayLap, int tong)
        {
            HoaDonNhapHang hd = new HoaDonNhapHang(idHD, idNguoiLap, ngayLap, tong);

            return(dataHDNH.Update(hd));
        }