public function set12HourClock($login, $use12HourClock)
    {
        $query = 'INSERT INTO ' . $this->table .
            ' (login, use_12_hour_clock) VALUES (?,?) ON DUPLICATE KEY UPDATE use_12_hour_clock=?';
        $bind  = array($login, $use12HourClock, $use12HourClock);
        Db::query($query, $bind);

        return true;
    }