A Database Error Occurred

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'UNION ALL SELECT lang, slug FROM `tb_article` WHERE parent_id = ORDER BY ' at line 2

SELECT lang, slug FROM `tb_article` WHERE article_id = UNION ALL SELECT lang, slug FROM `tb_article` WHERE parent_id = ORDER BY lang DESC

Filename: /data/hosting/home/kimiafa1/public_html/models/public/m_content.php

Line Number: 371