Oracle 查找每组其他行的最大值
我有一个简单的表,在GRP\U ID组中有一个值ID 使用分析函数很容易找到每组的最大值Oracle 查找每组其他行的最大值,oracle,analytic-functions,Oracle,Analytic Functions,我有一个简单的表,在GRP\U ID组中有一个值ID 使用分析函数很容易找到每组的最大值 select grp_id, id, max(id) over (partition by grp_id) max_grp from tst order by 1,2; GRP_ID ID MAX_GRP ---------- ---------- ---------- 1 1 2 1
select grp_id, id,
max(id) over (partition by grp_id) max_grp
from tst
order by 1,2;
GRP_ID ID MAX_GRP
---------- ---------- ----------
1 1 2
1 1 2
1 2 2
2 1 2
2 2 2
2 2 2
3 3 3
但目标是找到不包括当前行的值的最大值
这是预期结果列MAX_OTHER_ID:
请注意,在GRP_ID=2中,存在一个与MAX值相关的连接,因此MAX_OTHER_ID保持不变
我确实管理了这个两步解决方案,但我想知道是否有更直接、更简单的解决方案
with max1 as (
select grp_id, id,
row_number() over (partition by grp_id order by id desc) rn
from tst
)
select GRP_ID, ID,
case when rn = 1 /* MAX row per group */ then
max(decode(rn,1,to_number(null),id)) over (partition by grp_id)
else
max(id) over (partition by grp_id)
end as max_other_id
from max1
order by 1,2
) 我希望窗口功能支持多种范围规范,例如:
max(id) over (
partition by grp_id
order by id
range between unbounded preceding and 1 preceding
or range between 1 following and unbounded following
)
但不幸的是,他们没有
作为一种解决方法,您可以避免在不同的范围内两次使用该函数的子查询和CTE,并在该范围内调用coalesce
Coalesce是开箱即用的,因为ordering子句作为窗口函数调用的结果将是给定窗口中的max或null值
演示-
通过相关联查询获得预期结果!希望这有帮助。完美的解决方案。我被困在这个问题上有一段时间了,我正要告诉OP,它不能在一个查询中完成。这就是它的美妙之处,所以,你总是能学到一些新的东西。正ID的解决方案很好。@MarmiteBomber-我认为,是的。@GurV,这个限制可以被取消吗?同时给出负数的解决方案?@MarmiteBomber-更新了答案。请查收
with max1 as (
select grp_id, id,
row_number() over (partition by grp_id order by id desc) rn
from tst
)
select GRP_ID, ID,
case when rn = 1 /* MAX row per group */ then
max(decode(rn,1,to_number(null),id)) over (partition by grp_id)
else
max(id) over (partition by grp_id)
end as max_other_id
from max1
order by 1,2
max(id) over (
partition by grp_id
order by id
range between unbounded preceding and 1 preceding
or range between 1 following and unbounded following
)
select grp_id,
id,
coalesce(
max(id) over (
partition by grp_id
order by id
range between 1 following and unbounded following
)
, max(id) over (
partition by grp_id
order by id
range between unbounded preceding and 1 preceding
)
) max_grp
from tst
order by 1,
2
SELECT GRP_ID,ID, (SELECT Max(ID) FROM TEST A WHERE A.ROWID<>B.ROWID AND A.GRP_ID=B.GRP_ID) maX_ID FROM TEST B;