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SQL一对多特殊查询,取唯一一条

主表:

辅表:

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 ~~