public static function get($id)
 {
     global $db;
     $query = "SELECT * FROM `student_leaves_of_absence` where `id`=" . $db->qstr($id);
     $result = $db->GetRow($query);
     if ($result) {
         $fr = LeaveOfAbsence::fromArray($result);
         return $fr;
     }
 }
 public static function get(User $user)
 {
     global $db;
     $user_id = $user->getID();
     $query = "SELECT * FROM `student_leaves_of_absence` WHERE `user_id` = " . $db->qstr($user_id);
     $results = $db->getAll($query);
     $frs = array();
     if ($results) {
         foreach ($results as $result) {
             $fr = LeaveOfAbsence::fromArray($result);
             $frs[] = $fr;
         }
         return new self($frs);
     }
 }