php - 三张表,联表查询,这个sql还能再优化吗
本文介绍了php - 三张表,联表查询,这个sql还能再优化吗的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
问 题
SELECT c.username,c.sex,c.attentions,c.fans,a.id
,a.content
,a.isnum
,a.times
,a.turm
,a.keep
,a.comments
,a.uid
,b.mini
,b.mednum
,b.maxs
FROM (wb_userinfo c LEFT JOIN wb_weibo a ON c.uid = a.uid)
LEFT JOIN wb_picture b ON a.id
= b.wid
WHERE a.uid
IN(SELECT follow
FROM wb_follow WHERE fans
= 27) OR a.uid
= 27 ORDER BY a.times
LIMIT 0,10;
解决方案
有用or的可以考虑换成用union来尝试下
(SELECT c.username,c.sex,c.attentions,c.fans,a.id,a.content,a.isnum,a.times,a.turm,a.keep,a.comments,a.uid,b.mini,b.mednum,b.maxs
FROM (wb_userinfo c LEFT JOIN wb_weibo a ON c.uid = a.uid)
LEFT JOIN wb_picture b ON a.id = b.wid WHERE a.uid IN(SELECT follow FROM wb_follow WHERE fans = 27) )
union
(SELECT c.username,c.sex,c.attentions,c.fans,a.id,a.content,a.isnum,a.times,a.turm,a.keep,a.comments,a.uid,b.mini,b.mednum,b.maxs
FROM (wb_userinfo c LEFT JOIN wb_weibo a ON c.uid = a.uid)
LEFT JOIN wb_picture b ON a.id = b.wid WHERE a.uid = 27 )
ORDER BY a.times LIMIT 0,10;
这篇关于php - 三张表,联表查询,这个sql还能再优化吗的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文