protected function previewWrite($sql)
    {
        // Only preview if previewWrite is set, we are in dev mode, and
        // the query is mutable
        if (isset($_REQUEST['previewwrite'])
            && Director::isDev()
            && $this->connector->isQueryMutable($sql)
        ) {
            // output preview message
            Debug::message("Will execute: $sql");
            return true;
        } else {
            return false;
        }
    }