退出结帐页面时回滚

Question

我有一个ASP.NET结帐页面，它调用Page_Load方法中的方法

  private static void DecreaseStockCount(int itemID, int stockToBePurchased)
    {
        //get current stock count
        int stock = 0;
        using (OleDbConnection conn = new OleDbConnection(@"Provider=OraOLEDB.Oracle;Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=xe))); 
                                                          User Id=sys1;Password=admin;"))
            using (OleDbCommand cmd = new OleDbCommand())
            {
                cmd.Connection = conn;
                cmd.CommandText = string.Format("select stockcount from item_stock_mstr where itemid = '{0}'", itemID);

                conn.Open();

                using (OleDbDataReader reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        stock = Convert.ToInt32(reader.GetValue(0).ToString());
                    }
                }

                //if stockCount !=0, perform update to decrease stock count
                if ((stock != 0) && (stock > stockToBePurchased))
                {
                    stock = stock - stockToBePurchased;
                    cmd.CommandText = string.Format("update item_stock_mstr set stockcount = {0} where itemid = '{1}'", stock, itemID);
                    cmd.ExecuteNonQuery();
                }

                conn.Close();
            }
    }

该方法的作用是在结束结账前减少我的物品的库存数量。

我的问题是，当用户退出结帐页面而未完成结帐时，我无法将其回滚到上一个号码/重新更新。

我被困住了，请帮帮忙。