private void can_Delete_MouseDown(object sender, MouseButtonEventArgs e)
        {
            connect = new CTUConnection();// refreshens the 'Connection' class //

            try
            {
                connect.DeleteInvoice(int.Parse(ID));
                if (Department == 1)
                {
                    connect.SelectInvoiceNewVehicle();
                    DGV_Invoice.ItemsSource = connect.table.DefaultView;
                }

                else if (Department == 2)
                {
                    connect.SelectInvoiceOldVehicle();
                    DGV_Invoice.ItemsSource = connect.table.DefaultView;
                }

                else if (Department == 3)
                {
                    connect.SelectInvoiceService();
                    DGV_Invoice.ItemsSource = connect.table.DefaultView;
                }

                else if (Department == 4)
                {
                    connect.SelectInvoiceParts();
                    DGV_Invoice.ItemsSource = connect.table.DefaultView;
                }
            }

            catch (Exception)
            {
            }
        }