专题排行榜代码，会不会效率很低，都写一行了。

$hits = D('article')->field('yzm_article.id,yzm_article.catid,modelid,csign,aid,sid,tid,click')->
join("`yzm_special_content` ON yzm_special_content.aid=yzm_article.id")->
where($where)->order('click DESC')->limit('0,8')->select();