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 '-20,20' at line 1

select * from news where isvalid='1' and type='gonggao' order by listorder desc,posttime desc,id desc limit -20,20

Filename: /home/wwwroot/web/designer/controllers/news.php

Line Number: 62