public ActionResult AddProduct(Product product)
        {
            ProductDetail productDetail = product.ProductDetail;

            productDetail.masanpham = pro.ma;
            pro.ProductDetail       = productDetail;
            dao = new ProductsDao();
            bool check = dao.AddProduct(pro);

            if (check)
            {
                return(RedirectToAction("ProductManager", "HomeAd"));
            }
            else
            {
                return(JavaScript("<script>alert(\"Mã sản phẩm đã tồn tại\")</script>"));
            }
        }