DbClass.openConnection();

            DbClass.sql = "insert into ksiazki values ('"+Tytul.Text+"',"+Rok.Text+",'"+Autor.Text+"',"+Ilosc.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);



            DbClass.closeConnection();




            this.Close();