private function update_sync_cron_events()
 {
     $count = ExternalCalendarUsers::count();
     $events = CronEvents::findAll(array('conditions' => "name IN ('import_google_calendar','export_google_calendar')"));
     foreach ($events as $event) {
         if ($count > 0) {
             if (!$event->getEnabled()) {
                 $event->setEnabled(true);
                 $event->save();
             }
         } else {
             if ($event->getEnabled()) {
                 $event->setEnabled(false);
                 $event->save();
             }
         }
     }
 }