private void newPositionButton_Click(object sender, EventArgs e)
 {
     try {
         AddToOrderDTO position = new AddToOrderDTO
         {
             OrderIDKEY = _orderID,
             ItemIDKEY  = Convert.ToInt32(ItemIDOrder.Text),
             Amount     = Convert.ToInt32(AmountOrder.Text)
         };
         _customer.AddPosition(position);
         ItemIDOrder.Clear();
         AmountOrder.Clear();
     }
     catch
     {
         MessageBox.Show("Invalid data");
     }
 }