private void Szukaj_Click(object sender, RoutedEventArgs e)
        {
            DbClass.openConnection();
            DbClass.sql = "SELECT * FROM ksiazki WHERE tytul LIKE '%"+nazwa.Text+"%';";
            DbClass.cmd.CommandType = CommandType.Text;
            DbClass.cmd.CommandText = DbClass.sql;

            DbClass.da = new SqlDataAdapter(DbClass.cmd);
            DbClass.dt = new DataTable();
            DbClass.da.Fill(DbClass.dt);

            myDataGrid.ItemsSource = DbClass.dt.DefaultView;
            DbClass.closeConnection();
        }

        private void Nazwa_DragEnter(object sender, DragEventArgs e)
        {

        }

        private void Dodaj_Click(object sender, RoutedEventArgs e)
        {
            Dodawanie Dod = new Dodawanie();
            Dod.Show();
        }

        private void Refresh_Click(object sender, RoutedEventArgs e)
        {
            DbClass.openConnection();

            DbClass.sql = "SELECT * FROM ksiazki;";
            DbClass.cmd.CommandType = CommandType.Text;
            DbClass.cmd.CommandText = DbClass.sql;

            DbClass.da = new SqlDataAdapter(DbClass.cmd);
            DbClass.dt = new DataTable();
            DbClass.da.Fill(DbClass.dt);

            myDataGrid.ItemsSource = DbClass.dt.DefaultView;

            DbClass.closeConnection();
        }

        private void Usun_Click(object sender, RoutedEventArgs e)
        {
            Usuwanie Us = new Usuwanie();
            Us.Show();
        }

        private void Edit_Click(object sender, RoutedEventArgs e)
        {
            Edytowanie Ed = new Edytowanie();
            Ed.Show();
        }