public ActionResult UpdateStatus(int orderId, string status)
        {
            var _dh = new DonHang()
            {
                orderId = orderId, status = status
            };

            db.DonHangs.Attach(_dh);
            db.Entry(_dh).Property(X => X.status).IsModified = true;
            db.SaveChanges();
            return(RedirectToAction("Details", new { id = orderId }));
        }