A little fix:
with t ( ID , START_DATE , END_DATE ) as (
select 1 , date'2015-01-01' , date'2015-02-01' from dual union all
select 1 , date'2015-01-05' , date'2015-01-06' from dual union all
select 1 , date'2015-01-11' , date'2015-01-20' from dual union all
select 1 , date'2015-01-22' , date'2015-02-25' from dual union all
select 2 , date'2020-01-01' , date'2020-01-15' from dual union all
select 2 , date'2020-01-15' , date'2020-02-01' from dual union all
select 2 , date'2020-03-01' , date'2020-04-01' from dual union all
select 2 , date'2020-03-05' , date'2020-03-11' from dual
)
select
id,min(start_date),max(end_date)
from (
select id,start_date,end_date
,count(start_of_group) over(partition by id order by
start_date) grp
from (
select id,start_date,end_date
,case when start_date<=max(end_date)over(partition by id
order by start_date*,end_date* rows between unbounded preceding and 1
preceding)
then null
else 0
end start_of_group
from t
) v1
) v2
group by id,grp
order by id,grp
--
Best regards,
Sayan Malakshinov
http://orasql.org
