public void DemSoLuongSachTheoTheLoai()
        {
            SachTheoTheLoaiDAO sachTheoTheLoaiDAO = new SachTheoTheLoaiDAO();
            int SL = sachTheoTheLoaiDAO.GetSoLuongSachTheoMaLoai(ViewState["MaLoaiLayDuoc"].ToString());

            lblTongSoSach.Text = "Tìm được [" + SL.ToString() + "] sách";
        }
        private void LayDuLieuVaoDataList()
        {
            SachTheoTheLoaiDAO sachTheoTheLoaiDAO = new SachTheoTheLoaiDAO();

            DataList1.DataSource = sachTheoTheLoaiDAO.GetAllSachByMaLoai(ViewState["MaLoaiLayDuoc"].ToString());
            DataList1.DataBind();
        }