MySQL Query Error select id,title,subtitle,class from dx_kskm_news where class='参考书' and ejxk_id in ('080400','080402','080401','080456','080465','080463','080461','080462','080450','080451','080452','080455','080459','080454','080466','080467') order by kskm desc limit -50,50 Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in D:\wwwroot\dddjyky\wwwroot\lanmu2.php on line 330