private void addButton_Click(object sender, EventArgs e) { if (String.IsNullOrEmpty(customerIdTextBox.Text) || String.IsNullOrEmpty(itemNameTextBox.Text) || String.IsNullOrEmpty(quantityTextBox.Text)) { MessageBox.Show("Field Cant be Empty!"); return; } if (_orderManager.isOrderExist(Convert.ToInt32(customerIdTextBox.Text), itemNameTextBox.Text, Convert.ToInt32(quantityTextBox.Text))) { MessageBox.Show("Order Alredy Taken!!!"); return; } bool isAdded = _orderManager.AddData(Convert.ToInt32(customerIdTextBox.Text), itemNameTextBox.Text, Convert.ToInt32(quantityTextBox.Text)); if (isAdded) { MessageBox.Show("Order is Successful."); } else { MessageBox.Show("Order cant taken. "); } showOrderGridView.DataSource = _orderManager.ShowData(); }