public ActionResult Delete(int id=0)
 {
     //check
     if (!this._nhanvien_permission.Contains("phanhoi_delete"))
     {
         return this._fail_permission("phanhoi_delete");
     }
     PhanHoiController ctr = new PhanHoiController();
     if (!ctr.is_exist(id))
     {
         return RedirectToAction("Index", "AdminPhanHois");
     }
     //delete
     ctr.delete(id);
     return RedirectToAction("Index","AdminPhanHois");
 }