MySQL Query Error select id,title,subtitle,class from dx_kskm_news where class='参考书' and ejxk_id in ('030401','030404','030405','030457','030403','030402','030461','030400','030451','030452','030464','030460','030454','030459','030456','030463','030466','030465','030450','030462','030467','0304J1','0304J2','030468','030469','30405','30404','30403','30402','30401','030408','030406','030407') 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