public string PhatSinhMaTheLoai()
        {
            int    so  = theLoai_DAO.DemSoLuongTheLoai();
            string Ma  = "TL";
            int    dem = 0;

            foreach (char x in so.ToString())
            {
                dem++;
            }

            for (int i = 0; i < 8 - dem; i++)
            {
                Ma += "0";
            }

            Ma += so.ToString();

            return(Ma);
        }