private void btnPay_Click(object sender, EventArgs e) { if ((numCash.Value == 0 || Convert.ToDouble(lblBalance.Text) > 0) && lblTotalService.Text == "0.00") { MessageBox.Show("Full payment required when purchasing only products.", "Point of Sale", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } else if ((Convert.ToDouble(lblTotalAmount.Text) / 2) < Convert.ToDouble(lblBalance.Text) && lblTotalService.Text != "0.00") { MessageBox.Show("Partial payment must be at least half.", "Point of Sale", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } else { //select max+1 from tables where transaction has foreign key //assign those keys to a variable //insert first to tables where it is foreign key //then insert the same key to transaction table ContPointOfSale clspos = new ContPointOfSale(); ContPointOfSale.paid = Convert.ToDecimal(lblPaid.Text); ContPointOfSale.cash = numCash.Value; ContPointOfSale.balance = Convert.ToDecimal(lblBalance.Text); ContPointOfSale.change = Convert.ToDecimal(lblChange.Text); if (isOngoing) { contPos.UpdateToDb(); } else { contPos.SaveToDb(); } this.Close(); } }