public ActionResult giohang(int id)
        {
            string            a  = "";
            StationeryModelcs sc = new StationeryModelcs();

            if (Session["giohang"] == null)
            {
                List <GiohangModel> lg1 = new List <GiohangModel>();
                GiohangModel        gl  = new GiohangModel();
                gl.ProductName = sc.stati(id).ProductName;
                gl.Productid   = sc.stati(id).ProductId;
                gl.Quality     = Convert.ToInt32(sc.stati(id).Quantity);
                gl.Descript    = sc.stati(id).Description;
                gl.Soluong     = 1;
                lg1.Add(gl);
                Session["giohang"] = lg1;

                a += "<tr class='remove' >";
                a += String.Format("<td class='id'>{0}</td>", gl.Productid);
                a += String.Format("<td>{0}</td>", gl.ProductName);
                a += String.Format("<td>{0}</td>", gl.Quality);
                a += String.Format("<td>{0}</td>", gl.Descript);
                a += String.Format("<td><input type='type' name='sl' class='sl' value='{0}'  /></td>", gl.Soluong);
                a += String.Format("<td><button class='remove1'>Remove</button><input type='hidden' class='giatri1' value='{0}'></td></td>", gl.Productid);
                a += "</tr>";

                Response.Write(a);
            }
            else
            {
                if (TestProduct(id))
                {
                    string a1 = "";
                    updatequality(id);
                    List <GiohangModel> gh = (List <GiohangModel>)Session["giohang"];
                    foreach (GiohangModel g in gh)
                    {
                        a1 += "<tr class='remove'>";
                        a1 += String.Format("<td class='id'>{0}</td>", g.Productid);
                        a1 += String.Format("<td>{0}</td>", g.ProductName);

                        a1 += String.Format("<td>{0}</td>", g.Quality);
                        a1 += String.Format("<td>{0}</td>", g.Descript);
                        a1 += String.Format("<td><input type='type' name='sl' class='sl' value='{0}' /></td>", g.Soluong);
                        a1 += String.Format("<td><button class='remove1'>Remove</button><input type='hidden' class='giatri1' value='{0}'></td></td>", g.Productid);
                        a1 += "</tr>";
                    }
                    Response.Write(a1);
                }
                else
                {
                    List <GiohangModel> lg1 = (List <GiohangModel>)Session["giohang"];
                    Stationery          s1  = sc.stati(id);
                    GiohangModel        gm1 = new GiohangModel();
                    gm1.Productid   = s1.ProductId;
                    gm1.ProductName = s1.ProductName;
                    gm1.Quality     = Convert.ToInt32(s1.Quantity);
                    gm1.Soluong     = 1;
                    lg1.Insert(0, gm1);

                    Session["giohang"] = lg1;

                    string a2 = "";
                    foreach (GiohangModel g in (List <GiohangModel>)Session["giohang"])
                    {
                        a2 += "<tr class='remove'>";
                        a2 += String.Format("<td class='id'>{0}</td>", g.Productid);
                        a2 += String.Format("<td>{0}</td>", g.ProductName);

                        a2 += String.Format("<td>{0}</td>", g.Quality);
                        a2 += String.Format("<td>{0}</td>", g.Descript);
                        a2 += String.Format("<td><input type='type' name='sl' class='sl' value='{0}' /></td>", g.Soluong);
                        a2 += String.Format("<td><button class='remove1'>Remove</button><input type='hidden' class='giatri1' value='{0}'></td></td>", g.Productid);
                        a2 += "</tr>";
                    }
                    Response.Write(a2);
                }
            }
            return(null);
        }
        public ActionResult giohang(int id)
        {
            string a = "";
             StationeryModelcs sc = new StationeryModelcs();
             if (Session["giohang"] == null)
             {

                 List<GiohangModel> lg1 = new List<GiohangModel>();
                 GiohangModel gl = new GiohangModel();
                 gl.ProductName = sc.stati(id).ProductName;
                 gl.Productid = sc.stati(id).ProductId;
                 gl.Quality = Convert.ToInt32(sc.stati(id).Quantity);
                 gl.Descript = sc.stati(id).Description;
                 gl.Soluong = 1;
                 lg1.Add(gl);
                 Session["giohang"] = lg1;

                 a += "<tr class='remove' >";
                 a += String.Format("<td class='id'>{0}</td>", gl.Productid);
                 a += String.Format("<td>{0}</td>", gl.ProductName);
                 a += String.Format("<td>{0}</td>", gl.Quality);
                 a += String.Format("<td>{0}</td>", gl.Descript);
                 a += String.Format("<td><input type='type' name='sl' class='sl' value='{0}'  /></td>", gl.Soluong);
                 a += String.Format("<td><button class='remove1'>Remove</button><input type='hidden' class='giatri1' value='{0}'></td></td>", gl.Productid);
                 a += "</tr>";

                 Response.Write(a);
             }
             else
             {
                 if (TestProduct(id))
                 {
                     string a1 = "";
                     updatequality(id);
                     List<GiohangModel> gh = (List<GiohangModel>)Session["giohang"];
                     foreach (GiohangModel g in gh)
                     {
                         a1 += "<tr class='remove'>";
                         a1 += String.Format("<td class='id'>{0}</td>", g.Productid);
                         a1 += String.Format("<td>{0}</td>", g.ProductName);

                         a1 += String.Format("<td>{0}</td>", g.Quality);
                         a1 += String.Format("<td>{0}</td>", g.Descript);
                         a1 += String.Format("<td><input type='type' name='sl' class='sl' value='{0}' /></td>", g.Soluong);
                         a1 += String.Format("<td><button class='remove1'>Remove</button><input type='hidden' class='giatri1' value='{0}'></td></td>", g.Productid);
                         a1 += "</tr>";
                     }
                     Response.Write(a1);

                 }
                 else
                 {
                     List<GiohangModel> lg1 = (List<GiohangModel>)Session["giohang"];
                     Stationery s1 = sc.stati(id);
                     GiohangModel gm1 = new GiohangModel();
                     gm1.Productid = s1.ProductId;
                     gm1.ProductName = s1.ProductName;
                     gm1.Quality = Convert.ToInt32(s1.Quantity);
                     gm1.Soluong = 1;
                     lg1.Insert(0, gm1);

                     Session["giohang"] = lg1;

                     string a2 = "";
                     foreach (GiohangModel g in (List<GiohangModel>)Session["giohang"])
                     {
                         a2 += "<tr class='remove'>";
                         a2 += String.Format("<td class='id'>{0}</td>", g.Productid);
                         a2 += String.Format("<td>{0}</td>", g.ProductName);

                         a2 += String.Format("<td>{0}</td>", g.Quality);
                         a2 += String.Format("<td>{0}</td>", g.Descript);
                         a2 += String.Format("<td><input type='type' name='sl' class='sl' value='{0}' /></td>", g.Soluong);
                         a2 += String.Format("<td><button class='remove1'>Remove</button><input type='hidden' class='giatri1' value='{0}'></td></td>", g.Productid);
                         a2 += "</tr>";
                     }
                     Response.Write(a2);
                 }
             }
            return null;
        }