protected static function create_level_instances() {
        global $DB;

        $sql = "SELECT ".CONTEXT_COURSECAT.", cc.id
                  FROM {course_categories} cc
                 WHERE NOT EXISTS (SELECT 'x'
                                     FROM {context} cx
                                    WHERE cc.id = cx.instanceid AND cx.contextlevel=".CONTEXT_COURSECAT.")";
        $contextdata = $DB->get_recordset_sql($sql);
        foreach ($contextdata as $context) {
            context::insert_context_record(CONTEXT_COURSECAT, $context->id, null);
        }
        $contextdata->close();
    }