MYSQL count标量子查询怎么改left join，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
SELECT
homepageId,
userId,
homepagesummary,
totalviews,
totalleadpercents,
totalappointments,
homepagestatus,
linkphone,
imagepath,
createtime,
updatetime,
recommendtime,
sortcode,
designerimagepath,
isrecommend,
(
SELECT
count(*)
FROM
homepagexxxrelation
WHERE
homepageid = h.homepageid
AND groundingstatus = 0
) AS totalxxx,
(
SELECT
count(*)
FROM
homepagexxxrelation
WHERE
homepageid = h.homepageid
AND groundingstatus = 0
AND Createtime >= DATE_SUB(sysdate(), INTERVAL 7 DAY)
) AS weektotalxxx
FROM
designerhomepage h
WHERE
1 = 1 and isrecommend=1 order by weektotalxxx DESC,
homepageid DESC;
优化后:
SELECT
h.homepageId,
h.userId,
h.homepagesummary,
h.totalviews,
h.totalleadpercents,
h.totalappointments,
h.homepagestatus,
h.linkphone,
h.imagepath,
h.createtime,
h.updatetime,
h.recommendtime,
h.sortcode,
h.designerimagepath,
h.isrecommend,
ifnull(h3.cnt2,0) AS totalscheme,
ifnull(h3.cnt1,0) AS weektotalxxx
FROM
designerhomepage h
LEFT JOIN (
SELECT
Homepageid,
sum(case when HP.Createtime >= DATE_SUB(sysdate(), INTERVAL 7 DAY) then 1 else 0 end) cnt1,
count(*) cnt2
FROM
homepagexxxrelation hp
WHERE
HP.groundingstatus = 0
GROUP BY
Homepageid
) h3 ON h3.homepageid = h.homepageid
WHERE
1 = 1
and isrecommend=1
ORDER BY
weektotalxxx DESC,
homepageid DESC;看完上述内容，你们掌握MYSQL count标量子查询怎么改left join的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注亿速云行业资讯频道，感谢各位的阅读！
