通过hashtable和seesion操作购物车
我要把我的库存表信息通过下单添加到缓存表里面，现在库存表里面有两个主键卡号 cn_id和 卡号简写 e_reg。
Hashtable hstable;
  if (Session["ShopCart"] == null)
  {
  hstable = new Hashtable();
  hstable.Add(cn_id, Depotname); //添加一个项
  Session["ShopCart"] = hstable;
  }
else
  {
  //用户已经有购物车
  hstable = (Hashtable)Session["ShopCart"];
  if (hstable.Contains(cn_id) && hstable.Values.Equals(hstable[cn_id].ToString())) //如果表内有此该仓库下的卡号，不添加项
  {
  //int count = Convert.ToInt32(hstable[cn_id].ToString());
  //hstable[cn_id] = count + 1;
  }
  else
  hstable.Add(cn_id, Depotname); //如果没有此卡号，则新添加一个项
  Session["ShopCart"] = hstable;
  }
  Response.Redirect("shopcart.aspx");
到shopcart.aspx.cs里面添加数据
//取出存入Hashtable
  Hashtable hsCart = (Hashtable)Session["ShopCart"];
  if (hsCart.Count == 0)
  {
  TABLE1.Visible = false;
  Panel1.Visible = true;
  }
  else
  {  
  DataTable dtTable = new DataTable();
  DataColumn c1 = new DataColumn("No");
  DataColumn c2 = new DataColumn("CardId");
  DataColumn c3 = new DataColumn("DepotID");
  DataColumn c4 = new DataColumn("Depotname");
  DataColumn c5 = new DataColumn("Num");
  DataColumn c6 = new DataColumn("Price");
  DataColumn c7 = new DataColumn("TotalPrice");

  dtTable.Columns.Add(c1);
  dtTable.Columns.Add(c2);
  dtTable.Columns.Add(c3);
  dtTable.Columns.Add(c4);
  dtTable.Columns.Add(c5);
  dtTable.Columns.Add(c6);
  dtTable.Columns.Add(c7);


  DataRow row;
  //对数据表中进行启遍历，循环为第一列赋新值
  foreach (object key in hsCart.Keys)
  {
  row = dtTable.NewRow();
  row["CardId"] = key.ToString();
  //row["Num"] = hsCart[key].ToString();
  row["Depotname"] = hsCart[key].ToString();
  dtTable.Rows.Add(row);
  }

  int i = 1; //序号
  decimal price; //商品单价
  int count; // 商品数量
  decimal totalPrice = 0; //总数量  
  Model.Web_StockModel model = new Model.Web_StockModel();

  foreach (DataRow drRow in dtTable.Rows)
  {
  string myRow = drRow["CardId"].ToString();