Seems that you need a row generator. Here's an example.
Date format (just to know what you're looking at):
SQL> alter session set nls_date_format = 'dd.mm.yyyy hh24:mi:ss';
Session altered.
Query (creates 10 rows of data; change value in line #9 for more (or less) rows):
SQL> with temp (time_key, datum) as
2 (select 99, trunc(sysdate) datum from dual)
3 select
4 time_key + level time_key,
5 datum + ( 5 * (level - 1)) / (24 * 60) five_min,
6 datum + (10 * (level - 1)) / (24 * 60) ten_min,
7 datum + (15 * (level - 1)) / (24 * 60) fifteen_min
8 from temp
9 connect by level <= 10;
TIME_KEY FIVE_MIN TEN_MIN FIFTEEN_MIN
---------- ------------------- ------------------- -------------------
100 04.01.2021 00:00:00 04.01.2021 00:00:00 04.01.2021 00:00:00
101 04.01.2021 00:05:00 04.01.2021 00:10:00 04.01.2021 00:15:00
102 04.01.2021 00:10:00 04.01.2021 00:20:00 04.01.2021 00:30:00
103 04.01.2021 00:15:00 04.01.2021 00:30:00 04.01.2021 00:45:00
104 04.01.2021 00:20:00 04.01.2021 00:40:00 04.01.2021 01:00:00
105 04.01.2021 00:25:00 04.01.2021 00:50:00 04.01.2021 01:15:00
106 04.01.2021 00:30:00 04.01.2021 01:00:00 04.01.2021 01:30:00
107 04.01.2021 00:35:00 04.01.2021 01:10:00 04.01.2021 01:45:00
108 04.01.2021 00:40:00 04.01.2021 01:20:00 04.01.2021 02:00:00
109 04.01.2021 00:45:00 04.01.2021 01:30:00 04.01.2021 02:15:00
10 rows selected.
SQL>
In Oracle, there's no "time" datatype. We use date and it consists of both date AND time. Your example shows that you want time only; well, you can't have it, not as a date datatype. You can use e.g. TO_CHAR function on it (and fetch only time component). I wouldn't recommend you to store those values as strings into varchar2 datatype column as nothing prevents you (or someone else) to put e.g. 12:3f:75 into it, and that certainly isn't valid time value.
So, you'd then:
SQL> create table test as
2 with temp (time_key, datum) as
3 (select 99, trunc(sysdate) datum from dual)
4 select
5 time_key + level time_key,
6 datum + ( 5 * (level - 1)) / (24 * 60) five_min,
7 datum + (10 * (level - 1)) / (24 * 60) ten_min,
8 datum + (15 * (level - 1)) / (24 * 60) fifteen_min
9 from temp
10 connect by level <= 10;
Table created.
SQL> select time_key,
2 to_char(five_min, 'hh24:mi:ss') five_min
3 from test;
TIME_KEY FIVE_MIN
---------- --------
100 00:00:00
101 00:05:00
102 00:10:00
103 00:15:00
104 00:20:00
105 00:25:00
106 00:30:00
107 00:35:00
108 00:40:00
109 00:45:00
10 rows selected.
SQL>
To answer question T. Peter posted as a comment: I don't know for other databases, but - principle that should work elsewhere is to use a cross join (Cartesian product) with a subquery that returns "a lot of rows". In Oracle, ALL_OBJECTS is such a table. It isn't indefinite; in my sample schema, it contains ~8000 rows. For example (see lines #8 - 10):
SQL> with temp (time_key, datum) as
2 (select 99, trunc(sysdate) datum from dual)
3 select
4 time_key + rn time_key,
5 datum + ( 5 * (rn - 1)) / (24 * 60) five_min,
6 datum + (10 * (rn - 1)) / (24 * 60) ten_min,
7 datum + (15 * (rn - 1)) / (24 * 60) fifteen_min
8 from temp cross join (select rownum rn
9 from all_tables
10 where rownum <= 10
11 );
TIME_KEY FIVE_MIN TEN_MIN FIFTEEN_MIN
---------- ------------------- ------------------- -------------------
100 04.01.2021 00:00:00 04.01.2021 00:00:00 04.01.2021 00:00:00
101 04.01.2021 00:05:00 04.01.2021 00:10:00 04.01.2021 00:15:00
<snip>
Basically, keyword here is "row generator". I suggest you Google for it and add database name you use.
