行汇总，循环日期

Question

我想查看lead类型，如果该行的类型相同，则将这些日期合并以适合一行。

我有下表：

id    start_dt     end_dt    type
 1     1/1/19      2/21/19   cross
 1     2/22/19     6/5/19    cross
 1     6/6/19      8/31/19   cross
 1     9/1/19      10/3/19   AAAA
 1     10/4/19     10/4/19   cross
 1     10/5/19     10/6/19   AAAA
 1     10/7/19     10/10/19  AAAA
 1     10/11/19    12/31/99  cross

预期结果：

 id    start_dt    end_dt    type
 1     1/1/19      8/31/19   cross
 1     9/1/19      10/3/19   AAAA
 1     10/4/19     10/4/19   cross
 1     10/5/19     10/10/19  AAAA
 1     10/11/19    12/31/99  cross

如何使我的输出看起来像预期的结果？

我已经用leadlagrank和case expression进行了测试，但是没有值得在此处添加的内容。我在正确的道路上吗？

Answer 1

这是gaps-and-islands问题。使用：

select min(start_dt) as startdate, max(end_dt) as enddate, type
  from
  (
   with t(id, start_dt, end_dt,type) as
   (
    select 1, date'2019-01-01', date'2019-02-21', 'cross' from dual union all
    select 1, date'2019-02-22', date'2019-06-05', 'cross'  from dual union all
    select 1, date'2019-06-06', date'2019-08-31', 'cross'  from dual union all  
    select 1, date'2019-09-01', date'2019-10-03', 'AAAA'  from dual union all
    select 1, date'2019-09-04', date'2019-10-04', 'cross'  from dual union all   
    select 1, date'2019-10-05', date'2019-10-06', 'AAAA'  from dual union all
    select 1, date'2019-10-07', date'2019-10-10', 'AAAA'  from dual union all  
    select 1, date'2019-10-11', date'2019-12-31', 'cross'  from dual 
   )
   select type, 
          row_number() over (partition by id, type order by end_dt) as grp,
          row_number() over (partition by id order by end_dt) as rn,
          start_dt, end_dt
     from t
   ) tt
 group by type,grp - rn
 order by enddate;

STARTDATE   ENDDATE     TYPE
---------   ---------   -----
01-JAN-19   31-AUG-19   cross
01-SEP-19   03-OCT-19   AAAA
04-SEP-19   04-OCT-19   cross
05-OCT-19   10-OCT-19   AAAA
11-OCT-19   31-DEC-19   cross

Demo