mysql索引问题

问题描述

$query = $this->db->query(’SELECT * , comments.rank1+comments.rank2+comments.rank3+comments.rank4 as ranksum,sites.id as id FROM sites inner join comments on sites.siteurl=comments.siteurl WHERE sites.tj<3 and sites.isshow=1 order by ranksum desc limit 10’);return $query->result_array();

comments.rank是针对站点的评价，每个页面都有这一部分：在页面右侧显示评价总分最高的10个站点。但是每个页面都做这么一次查询是不是不太好啊，能不能写成索引的形式，求助大神

问题解答

SELECT *, comments.rank1 + comments.rank2 + comments.rank3 + comments.rank4 AS ranksum, sites.id AS idFROM sitesINNER JOIN comments ON sites.siteurl = comments.siteurlWHERE sites.tj < 3AND sites.isshow = 1ORDER BY ranksum DESCLIMIT 10