private function deleteFormAnswers($qsID)
    {
        $db = Loader::db();
        $v = [intval($qsID)];
        $q = 'SELECT asID FROM btFormAnswerSet WHERE questionSetId = ?';

        $r = $db->query($q, $v);
        while ($row = $r->fetchRow()) {
            $asID = $row['asID'];
            $this->deleteAnswers($asID);
        }
    }