MYSQL count標量子查詢怎么改left join

MYSQL count標量子查詢怎么改left join，相信很多沒有經驗的人對此束手無策，為此本文總結了問題出現的原因和解決方法，通過這篇文章希望你能解決這個問題。

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;
優化后:
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;

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