private void BtnDeleteCustomer_Click(object sender, RoutedEventArgs e)
        {
            if (!Validation())
            {
                return;
            }

            if (MessageBox.Show("Do you want to delete this Customer?", "Question", MessageBoxButton.YesNo, MessageBoxImage.Information) == MessageBoxResult.Yes)
            {
                dr.DeleteCustomer(cr.Id);
                btnAddCustomer.Visibility    = Visibility.Visible;
                btnUpdateCustomer.Visibility = Visibility.Hidden;
                btnDeleteCustomer.Visibility = Visibility.Hidden;
                FillDG();
                ResetTextBox();
            }
        }