public function delete()
 {
     $sql = "DELETE FROM edt_calendrier_manager WHERE id = '" . $this->id . "' ";
     $req = mysqli_query($GLOBALS["mysqli"], $sql);
     if ($req) {
         // ======== Suppression des périodes calendaires
         $PeriodesCalendaires = new PeriodeCalendaire();
         $PeriodesCalendaires->id_calendar = $this->id;
         if ($PeriodesCalendaires->deleteCalendar()) {
             // ========= Suppression des liaisons classes <-> calendar
             $jointure = new jointure_calendar_classes();
             $jointure->id_calendar = $this->id;
             if ($jointure->delete_classes()) {
                 return true;
             } else {
                 return false;
             }
         } else {
             return false;
         }
     } else {
         return false;
     }
 }