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。
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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;
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