public void payOrder(string oID, decimal payment) { var test = new DatabaseConn(); // toDo: 1 insert for payment var present_pay = test.Select("order_payment", "SUM(payment)") .NJoin("orders") .Where("order_id", oID) .Group("order_id") .GetQueryData() .Rows[0][0]; decimal total_pay = Convert.ToDecimal(present_pay) + payment; MessageBox.Show(total_pay.ToString()); test.Insert("order_payment", "order_id", oID, "payment", payment.ToString(), "payment_date", DateTime.Now.ToString("yyyy-MM-dd")) .GetQueryData(); var total_price = test.Select("orderline", "SUM(total_price)") .Where("order_id", oID) .Group("order_id") .GetQueryData() .Rows[0][0]; if (total_pay >= total_price) { test.Update("orders", "payment_status", "1") .Where("order_id", oID) .GetQueryData(); } showOrderDetails(); }