private string GenerateBookId()
        {
            DataTable dataTable = bUS.GetDatasByCommand("SELECT MaSach FROM SACH ORDER BY MaSach");
            int       oldBookId = int.Parse(dataTable.Rows[dataTable.DefaultView.Count - 1]["MaSach"].ToString().Substring(1, 3));

            oldBookId++;

            string newBookId = "S" + oldBookId.ToString("000");

            return(newBookId);
        }
        DataTable LoadDsSach()
        {
            SachBUS bus = new SachBUS();
            string  str = "SELECT MaSach FROM SACH";

            return(bus.GetDatasByCommand(str));
        }