public static function get(User $user)
 {
     global $db;
     $user_id = $user->getID();
     $query = "SELECT * FROM `student_contributions` WHERE `user_id` = " . $db->qstr($user_id) . " ORDER BY `start_year` DESC, `start_month` DESC";
     $results = $db->getAll($query);
     $contributions = array();
     if ($results) {
         foreach ($results as $result) {
             $contribution = Contribution::fromArray($result);
             $contributions[] = $contribution;
         }
     }
     return new self($contributions);
 }
 /**
  * 
  * @param int $id
  * @return Contribution
  */
 public static function get($id)
 {
     global $db;
     $query = "SELECT * FROM `student_contributions` WHERE `id` = " . $db->qstr($id);
     $result = $db->getRow($query);
     if ($result) {
         $contribution = Contribution::fromArray($result);
         return $contribution;
     }
 }