Question

我有下表

ID      Date     Indicator
12345   1/1/2001   N
12345   2/1/2001   N
12345   3/1/2001   N
12345   4/1/2001   Y
12345   5/1/2001   Y
12345   6/1/2001   Y
67891   2/1/2002   N
67891   3/1/2002   N
67891   4/1/2002   Y
67891   5/1/2002   Y
67891   6/1/2002   Y

我想拉出指标更改的第一行，例如

ID      Date     Indicator
12345   1/1/2001   N
12345   4/1/2001   Y
67891   2/1/2002   N
67891   4/1/2002   Y

并且只有指标发生变化的第二行

ID      Date     Indicator
12345   4/1/2001   Y
67891   4/1/2002   Y

Answer 1

使用分析功能的三步解决方案如下所示。我假设你的桌子是TEST

-- add IS_CHANG E= 'Y' for change in Indicator
with test1 as (
select a.*,
case when lag(indicator,1,'X') over (partition by ID order by date_d) != indicator then 'Y' end as is_change
from test a),
-- filter changes only and numerate records
test2 as (
select a.*,
row_number() over (partition by id order by date_d) as RN
from test1 a
where is_change = 'Y')
-- get only 2nd change
select ID, DATE_D, INDICATOR from test2
where rn = 2
;

Group by和Max不适用于此问题

1 个答案: