public function subtractOneNumber($journalVoucherIds, $databaseConnectionName = null)
  {
    if(empty($databaseConnectionName))
    {
      $databaseConnectionName = $this->databaseConnectionName;
    }

    $this->JournalVoucher->setConnection($databaseConnectionName)
      ->whereIn('id', $journalVoucherIds)
      ->update(array('number' => $this->DB->raw('number - 1')));

    return true;
  }