仅按连接表最大值选择行 [英] Select only rows by join tables max value

问题描述

我只想为 u.classno、u.userno 选择具有最大 b.enddate 的行.但它不起作用.

I want to select only the row which has max b.enddate for u.classno, u.userno. But it doesn't work.

select u.classno, u.userno, b.enddate
from libUser u
join book b on b.id = u.bookid
group by u.classno, u.userno
having b.enddate=max(b.enddate) //doesn't works

推荐答案

有什么问题:

select u.classno, u.userno, MAX(b.enddate)
from libUser u
join book b on b.id = u.bookid
group by u.classno, u.userno

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