MySQL Query Error select id,title,subtitle,class from dx_kskm_news where class='参考书' and ejxk_id in ('045115','045117','045102','045103','045104','045105','045106','045107','045108','045109','045110','045111','045112','045113','045114','045116','045101','045118','045100','045120','045119','45100','45106','45114','45101','45115','45116','45109','45102','45107','45104','45103','45105','45108','45120','45112','45110') order by kskm desc limit -1700,50 Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in D:\wwwroot\dddjyky\wwwroot\lanmu2.php on line 330