public ViewResult ChiTietSach(int masach = 0) { Sach sach = sachDAO.ChiTietSach(masach); if (sach == null) { Response.StatusCode = 404; return(null); } var chude = sach.MaChuDe; if (sach.SoLuong == 0) { ViewBag.Soluong = "Hết Hàng"; } else { ViewBag.Soluong2 = "Còn Hàng"; } return(View(sach)); }