Q:

Row lumping, cycle dates

I want to look at the lead type and if that type is the same for that row then merge in those dates to fit within one row.  
I have the below table:
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

Expected Results:
 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

How can I get my output to look like the expected results?
I have tested withlead lag rank and case expression but nothing worthy of adding here. Am I on the right path?

A:

This is a gaps-and-islands problem. One option for solving it through contribution of row_number() analytical function :
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 rn1,
          row_number() over (partition by id order by end_dt) as rn2,
          start_dt, end_dt
     from t
   ) tt
 group by type, rn1 - rn2
 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

