댓글기능에 아래와 같이 오류메시지가 뜨는데요..

어떤 오류인지요..

MySQL 메시지 1054:
Unknown column 'parent_uid' in 'where clause'
SQL 질의:
SELECT * FROM `wp_kboard_comments` WHERE content_uid='4' AND parent_uid<=0 ORDER BY uid ASC