private void btnCreate_Click(object sender, EventArgs e) { if (Phone.Equals("")) { MessageBox.Show("Please fill the phone"); } else { string err = ""; if (!vl.CheckPhone(Phone)) { err += "Phone is a string has 10 number.\n"; } if (err.Equals("")) { if (products.Count > 0) { MCusP.AddCustomer(); orderID = MOP.AddOrder(); MDP.AddDetail(); MCP.UpdateQuantityProduct(); MessageBox.Show("OK"); LoadCar(); products.Clear(); LoadCart(); } else { MessageBox.Show("No product added"); } } else { MessageBox.Show(err); } } }