MySQL Query Error select id,title,subtitle,class from dx_kskm_news where class='参考书' and ejxk_id in ('090101','090102','090163','090160','090169','090100','090157','090162','090154','090166','090156','090165','090151','090158','090161','090167','090171','090152','090153','090170','090173','090155','090174','090176','090175','090177','090164','090178','090180','090179','0901J2','090181','090182','090183','090184','0901J1') order by kskm desc limit -450,50 Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in D:\wwwroot\dddjyky\wwwroot\lanmu2.php on line 330