public function addEventToGroup(EventModel $event, GroupModel $group)
 {
     $stat = $this->siteContainer['databasehelper']->getPDO()->prepare("SELECT * FROM event_in_group WHERE group_id=:group_id AND " . " event_id=:event_id ");
     $stat->execute(array('group_id' => $group->getId(), 'event_id' => $event->getId()));
     if ($stat->fetch()) {
         return;
     }
     $stat = $this->siteContainer['databasehelper']->getPDO()->prepare("INSERT INTO event_in_group " . "(event_id, group_id )" . " VALUES " . "(:event_id, :group_id)");
     $stat->execute(array('event_id' => $event->getId(), 'group_id' => $group->getId()));
 }