我需要查询一个包含step id + value的表。 结果将列出间隔及其相关值。 这里的间隔被定义为"连续的步骤ID,共享相同的数据值"。
我很难用文字描述它,所以请看这个:
从此表
Step ! Data
------------
1 ! A
2 ! A
3 ! A
5 ! A
6 ! B
10 ! A
我需要以下报告
From ! To ! Data
-------------------
1 ! 3 ! A
5 ! 5 ! A
6 ! null ! B
10 ! null ! A
我认为导演()会帮助我,但没有成功。
答案 0 :(得分:1)
您可以通过生成一系列数字并从step
中减去来实现此目的。当值是连续的时,这将是一个常量:
select min(step) as from_step, max(step) as to_step, data
from (select t.*,
row_number() over (partition by data order by step) as seqnum
from t
) t
group by (step - seqnum), data;
编辑:
目前尚不清楚NULL
来自哪里。如果我推测它们是每个值的最后一个值,你可以这样做:
select min(step) as from_step,
(case when max(step) <> max_step then max(step) end) as to_step,
data
from (select t.*,
max(step) over (partition by data) as max_step
row_number() over (partition by data order by step) as seqnum
from t
) t
group by (step - seqnum), data, max_step;
答案 1 :(得分:1)
select min (step) as "from"
,nullif (max (step),max(min(step)) over (partition by data)) as "to"
,data
from (select step,data
,row_number () over (partition by data order by step) as n
from t
)
group by data
,step - n
order by "from"