private void BtnDeleteProduct(object sender, RoutedEventArgs e)
        {
            Product p = new Product();

            p.ProductID = long.Parse(txtProdId.Text);

            string msg = da.DeleteProduct(p);

            MessageBox.Show("" + msg);
            if (msg.Equals("Product Discontinued"))
            {
                MainWindow mw = Application.Current.Windows.OfType <MainWindow>().FirstOrDefault();
                if (mw != null)
                {
                    mw.MainFrame.Content = new ManageProducts();
                }
            }
        }