WITH t(start,stop,color,priority) as (
select 40,60,'красный',1 from dual union all
select 100,110,'красный',1 from dual union all
select 20,50,'желтый',2 from dual union all
select 80,90,'желтый',2 from dual union all
select 10,70,'синий',3 from dual union all
select 80,110,'синий',3 from dual
)
select * from t;

-- table 1 with column list
with user_tab(user_id,user_name,registry_date) as (
select 1,'Bob',to_date('11.02.1921 23:04:44','DD.MM.YYYY HH24:MI:SS') from dual union all
select 2,'Max',to_date('11.02.1922 23:04:44','DD.MM.YYYY HH24:MI:SS') from dual union all
select 3,'Jon',to_date('11.02.1923 23:04:44','DD.MM.YYYY HH24:MI:SS') from dual
)
-- table 2 with column list
,user_post(post_id,user_id,parent_post_id,post_date,message) as (
select 100,1,null,to_date('11.02.1923 23:04:00','DD.MM.YYYY HH24:MI:SS'),'Hi' from dual union all
select 101,2,100,to_date('11.02.1923 23:05:23','DD.MM.YYYY HH24:MI:SS'),'Hi' from dual union all
select 102,3,100,to_date('11.02.1923 23:05:35','DD.MM.YYYY HH24:MI:SS'),'Hi' from dual union all
select 103,1,102,to_date('11.02.1923 23:06:00','DD.MM.YYYY HH24:MI:SS'),'How are you' from dual union all
select 104,2,102,to_date('11.02.1923 23:07:05','DD.MM.YYYY HH24:MI:SS'),'All right!' from dual union all
select 105,1,101,to_date('11.02.1923 23:06:21','DD.MM.YYYY HH24:MI:SS'),'Bye' from dual union all
select 106,1,104,to_date('11.02.1923 23:04:37','DD.MM.YYYY HH24:MI:SS'),'Bye' from dual union all
select 107,2,null,to_date('11.02.1923 23:08:56','DD.MM.YYYY HH24:MI:SS'),'Hmm' from dual
)
-- query sample
select
-- level
-- ,u.user_name
-- ,p.message
rpad(to_char(p.post_date,'YYYY-MM-DD HH24:MI:SS  '),20+level*2,' ')||u.user_name||': '||p.message as txt
from 
 user_post p
 join user_tab  u on ( p.user_id = u.user_id)
where p.post_date >= u.registry_date
start with p.parent_post_id is null 
connect by prior p.post_id=p.parent_post_id 
;

TXT
--------------------------------------------------------------------------------
1923-02-11 23:04:00   Bob: Hi
1923-02-11 23:05:23     Max: Hi
1923-02-11 23:06:21       Bob: Bye
1923-02-11 23:05:35     Jon: Hi
1923-02-11 23:06:00       Bob: How are you
1923-02-11 23:07:05       Max: All right!
1923-02-11 23:04:37         Bob: Bye
1923-02-11 23:08:56   Max: Hmm

8 rows selected.