private void Button_Click(object sender, RoutedEventArgs e)
        {
            Publisher pub = (Publisher)gvPublisher.DataContext;

            if (pub.Id != 0)
            {
                db.EditPublisher(pub);
            }
            else
            {
                db.AddPublisher(pub);
            }
            lwPublishers.ItemsSource = db.GetAllPubs();
            gvPublisher.DataContext  = new Publisher();
        }