protected void BtnSubmit_Click(object sender, EventArgs e)
    {
        ProductsModel productsModel = new ProductsModel();
        Product       product       = CreateProduct();

        if (!String.IsNullOrWhiteSpace(Request.QueryString["id"]))
        {
            int id = Convert.ToInt32(Request.QueryString["id"]);
            lblResult.Text = productsModel.UpdateProduct(id, product);
        }
        else
        {
            lblResult.Text = productsModel.InsertProduct(product);
        }
    }