[英]How to get the max value for each group in Oracle?
select * from table
where (team, age) in (select team, max(age) from table group by team)
一种方法使用keep
:
select team, max(age) as age,
max(person) keep (dense_rank first order by age desc) as person
from t
group by team;
还有其他方法,但根据我的经验, keep
效果很好。
这是一个没有keep
但有row_number()
的例子:
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;
select * from (select person,team,age,
dense_rank() over (partition by team order by age desc) rnk)
where rnk=1;
使用分析函数返回每个团队的所有最大年龄的人(如果有相同年龄的人需要),只选择一次表,因此比多次引用表的其他解决方案更快:
With MaxAge as (
Select T.*, Max (Age) Over (Partition by Team) MaxAge
From Table T
)
Select Person, Team, Age From MaxAge Where Age=MaxAge
;
这也适用于 MySQL/MariaDB。
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