Вот как я понял вопрос.
SQL> alter session set nls_date_format = 'dd.mm.yyyy hh24:mi';
Session altered.
SQL> break on period;
SQL> with
2 data (id, datum) as
3 (select 1, to_date('01.04.2019 15:30', 'dd.mm.yyyy hh24:mi') from dual union all
4 select 2, to_date('01.04.2019 20:00', 'dd.mm.yyyy hh24:mi') from dual union all -- 1st
5 select 3, to_date('02.04.2019 01:15', 'dd.mm.yyyy hh24:mi') from dual union all -- 1st perios
6 select 4, to_date('02.04.2019 11:00', 'dd.mm.yyyy hh24:mi') from dual union all
7 select 5, to_date('02.04.2019 23:15', 'dd.mm.yyyy hh24:mi') from dual union all -- 2nd period
8 select 6, to_date('03.04.2019 00:10', 'dd.mm.yyyy hh24:mi') from dual union all -- 2nd
9 select 7, to_date('04.04.2019 22:20', 'dd.mm.yyyy hh24:mi') from dual -- 3rd period
10 ),
11 test as
12 (select date '2019-04-01' dstart,
13 date '2019-04-06' dend
14 from dual
15 ),
16 inter as
17 (select dstart + level - 1 datum
18 from test
19 connect by level <= dend - dstart + 1
20 ),
21 from_to as
22 (select datum + 19/24 date_from,
23 lead(datum) over (order by datum) + 8/24 date_to
24 from inter
25 )
26 select f.date_From ||' - '|| f.date_to period,
27 d.id,
28 d.datum
29 from data d join from_to f on 1 = 1
30 where d.datum between f.date_from and f.date_to
31 order by f.date_From, d.id;
PERIOD ID DATUM
----------------------------------- ---------- ----------------
01.04.2019 19:00 - 02.04.2019 08:00 2 01.04.2019 20:00
3 02.04.2019 01:15
02.04.2019 19:00 - 03.04.2019 08:00 5 02.04.2019 23:15
6 03.04.2019 00:10
04.04.2019 19:00 - 05.04.2019 08:00 7 04.04.2019 22:20
SQL>