如何获得Oracle中每个组的最大值？

Question

我发现了一些针对此问题的解决方案，但是，它们似乎不适用于Oracle。

我得到这个：

我想以目前大约只有年龄最大的人每队的信息。所以，我的输出应该是这样的：

PERSON | TEAM | AGE 
Sam  | 1 | 23 
Michael | 2 | 21 

我怎么能在Oracle中做到这一点？

Answer 1

一种方法是使用keep：

select team, max(age) as age, 
     max(person) keep (dense_rank first order by age desc) as person 
from t 
group by team; 

还有其他的方法，但以我的经验，keep工作得很好。

Answer 2

下面是一个例子，而不keep但row_number()：

with t0 as 
(
    select person, team, age, 
    row_number() over(partition by team order by age desc) as rn 
    from t 
) 
select person, team, age 
from t0 
where rn = 1; 

Answer 3

select * from table 
where (team, age) in (select team, max(age) from table group by team)