public ActionResult Buy(string phone, string name)
        {
            // lưu bảng bill -> idbill

            BillDao dao  = new BillDao();
            Bill    bill = new Bill();

            bill.username = name;
            bill.iduser   = phone;
            int id = dao.Add(bill);

            ShoppingCart cart = (ShoppingCart)Session["cart"];

            if (cart != null)
            {
                List <ItemCart>  ListCart = cart.ListItem;
                List <BilDetail> ls       = new List <BilDetail>();
                for (int i = 0; i < ListCart.Count; i++)
                {
                    BilDetail billdetail = new BilDetail();
                    billdetail.idbill    = idbill;
                    billdetail.idproduct = idproduct;
                    billdetail.quantity  = ListCart[i].quantity;
                    billdetail.prict     = (decimal)ListCart[i].price;
                    ls.Add(billdetail);
                    // lưu bảng billandProduct
                    dao.addBillDetai(ls);
                }
            }
            Session["cart"] = null;
            return(View());
        }