Query Error

MySQL Query SELECT id,title,summary,image, created_time,alias,category_alias,category_id,category_name,tags_recommend,tags FROM articles_items WHERE ( title like '%Tây Bắc%' OR tags like '%Tây Bắc%' ) ORDER BY id DESC, ordering DESC LIMIT -18,18
Line Error1064 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 '-18,18' at line 1