private void ButtonAdd_Click_1(object sender, EventArgs e)
        {
            DataRow[] vehicleRowData    = vehicledata.Select("VehicleType='" + ComboBoxVehicleModel.Text.Trim() + "' AND VehicleName='" + ComboBoxVehicleName.Text.Trim() + "'");
            string    selectedVehicleId = vehicleRowData[0]["Id"].ToString().Trim();

            DataRow[] itemRowData = itemsData.Select("VehicleId = '" + selectedVehicleId + "' AND ItemName = '" + ComboBoxItemName.Text.Trim() + "'");
            string    itemid1     = itemRowData[0]["ItemId"].ToString().Trim();

            if (ComboBoxItemName.Items.Contains(ComboBoxItemName.Text))
            {
                DataTable dataTable = (DataTable)dataGridItems.DataSource;
                DataRow   drToAdd   = dataTable.NewRow();
                drToAdd["ItemName"] = ComboBoxItemName.Text.ToString();
                drToAdd["Quantity"] = NumericQuantity.Value.ToString();
                drToAdd["price"]    = NumericUnitPrice.Value.ToString();
                drToAdd["Tax"]      = ComboboxItemTax.Text;
                drToAdd["ItemNo"]   = itemid1;
                //calculate total without tax
                decimal total = (Convert.ToDecimal(NumericQuantity.Value) * Convert.ToDecimal(NumericUnitPrice.Value));
                //add tax
                total = total + (total * (Convert.ToDecimal(ComboboxItemTax.Text) / 100));
                dataTable.Rows.Add(drToAdd);
                dataTable.AcceptChanges();
                loadTotalAndSubTotal();                 //this here is not effecient change this
                ComboBoxItemName.Focus();
            }
            else
            {
                MessageBox.Show("Please add the new item before adding this to the invoice");
                ComboBoxItemName.Focus();
            }
        }
 private void ComboBoxItemName_Leave(object sender, EventArgs e)
 {
     if (!ComboBoxItemName.Items.Contains(ComboBoxItemName.Text))
     {
         DialogResult result = MessageBox.Show("the item does not exist, would you like to add a new item?", "Confirmation", MessageBoxButtons.YesNo);
         if (result == DialogResult.Yes)
         {
             NewService NewServiceObj = new NewService(ComboBoxVehicleModel.Text.Trim(), ComboBoxVehicleName.Text.Trim(), ComboBoxItemName.Text.Trim());
             NewServiceObj.ShowDialog();
             getItemsData();
             ComboBoxItemName.Text = "";
             ComboBoxItemName.Focus();
         }
         ComboBoxItemName.Text = "";
     }
 }