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SQL一对多特殊查询,取唯一一条

时间:2022-03-15 18:21

主表:

技术图片

辅表:

技术图片

一个app对应多个apk,现在要取上线(Apk_Status最大的)的应用

select * from [dbo].[tbl_APP] as app 
join 

(select * from [dbo].[tbl_Apk] as AA where not exists(select top 1 * from tbl_Apk as BB where AA.Apk_APPId=BB.Apk_APPId and AA.Apk_Status < BB.Apk_Status))

 as apk on app.APP_Id = apk.Apk_APPId

重点是取关联的右表:

select * from [dbo].[tbl_Apk] as AA where not exists(select top 1 * from tbl_Apk as BB where AA.Apk_APPId=BB.Apk_APPId and AA.Apk_Status < BB.Apk_Status)

没看懂这个not exists的逻辑 ~~

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