static public function getClientId()
  {

    TransferCollection::checkId();

    $query = "SELECT id_client FROM transfers WHERE id = '".$_GET['id']."'";
    $qres=mysql_query($query);
    $row=mysql_fetch_assoc($qres);

    if(empty($row))
      die('wrong id, please contact admin.');

    die($row['id_client']);
    return ($row['id_client']);
  }