Suggestions::getNumVotesBySuggestion PHP Метод

    private function getNumVotesBySuggestion($suggestId)
    {
        $sth = $this->db->prepare("SELECT COALESCE(SUM(voteWeight),0) FROM suggestions_votes WHERE suggestionId = ?");
        $sth->bindParam(1, $suggestId, PDO::PARAM_INT);
        $sth->execute();
        $res = $sth->fetch();
        return $res[0];
    }