/**
  * delete
  *
  * @access public
  * @return
  */
 public function delete()
 {
     global $ilDB;
     include_once './Services/Calendar/classes/class.ilCalendarRecurrence.php';
     ilCalendarRecurrence::_delete($this->getEntryId());
     $query = "DELETE FROM cal_entries " . "WHERE cal_id = " . $this->db->quote($this->getEntryId(), 'integer') . " ";
     $res = $ilDB->manipulate($query);
     include_once './Services/Calendar/classes/class.ilCalendarCategoryAssignments.php';
     ilCalendarCategoryAssignments::_deleteByAppointmentId($this->getEntryId());
     return true;
 }