怎么查询数量Amount，还有金额等于价格Price乘以数量，代码怎么写 点击一下购买按钮，数量Amount加一，就是可以重复购买

[qq_33426639]

怎么查询数量Amount，还有金额等于价格Price乘以数量，代码怎么写
点击一下购买按钮，数量Amount加一，就是可以重复购买

 //查询订单
        private void getBuyMobiles()
        {
            SqlConnection cn = new SqlConnection(Properties.Settings.Default.eShopConnectionString);
            string sql = "SELECT OrderItems.*,MobileName FROM OrderItems,Mobiles";
            sql += " WHERE OrderItems.MobileID=Mobiles.MobileID";
            sql += " ORDER BY Price";
            SqlDataAdapter da = new SqlDataAdapter(sql, cn);
            da.SelectCommand.Parameters.Add("UserName", SqlDbType.NVarChar, 8).Value = CPublic.LogInfo
          ["UserName"].ToString();
            cn.Open();
            da.Fill(ds, "OrderItems");
            cn.Close();
            dgvSelectMobiles.DataSource = ds.Tables["OrderItems"];


   //实现购买逻辑
        private void BMobiles()
        {
            if (dgvMobiles.CurrentRow != null)
            {
                string MobileID = dgvMobiles.CurrentRow.Cells["MobileID"].Value.ToString();
               
                string Price = dgvMobiles.CurrentRow.Cells["Price"].Value.ToString();
               DataRow[] adr;
                adr = ds.Tables["OrderItems"].Select("MobileID='" + MobileID + "'");
                if (adr.Length == 0)
                {
            string MobileName = dgvMobiles.CurrentRow.Cells["MobileName"].Value.ToString();
            DataRow dr =ds.Tables["OrderItems"].NewRow();
            dr["MobileID"] = MobileID;
             dr["MobileName"] = MobileName;
             dr["Price"] = Price;
            
             ds.Tables["OrderItems"].Rows.Add(dr);

        }
                else
                {
                   

                }
         }
         }



  //查询所有商品
        private void getMobiles()
        {
            SqlConnection cn = new SqlConnection(Properties.Settings.Default.eShopConnectionString);
            string sql = "SELECT * FROM Mobiles ORDER BY MobileID";
            SqlDataAdapter da = new SqlDataAdapter(sql, cn); 
            cn.Open();
            da.Fill(ds, "Mobiles");
            cn.Close();
            dgvMobiles.DataSource = ds.Tables["Mobiles"];
        }