protected function get_iterator() {
        global $DB;

        // Build the SQL dynamically here
        $fieldslist = 't.' . implode(', t.', $this->fields);
        $sql = "SELECT t.id, $fieldslist
                  FROM {" . $this->tablename . "} t
                  JOIN {backup_ids_temp} b ON b.newitemid = t.id
                 WHERE b.backupid = ?
                   AND b.itemname = ?
                   AND t.blockname = 'html'";
        $params = array($this->restoreid, $this->mapping);
        return ($DB->get_recordset_sql($sql, $params));
    }