Group by Hour for Epoch time - sql

Question

I need to group by Hour for converted epoch time, here is what I have done but it is still grouping by the day. Can anyone support?
select count (*) as "Total",to_char(trunc(to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME),'DD/MM/YYYY HH24') as "Day"
from Records
where ID=35 and (INSERTION_TIME/86400)+ to_date('01-01-1970 00:00:00','dd-mm-yyyy HH24:MI:SS') >=sysdate - 4
group by trunc(to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME)
order by trunc(to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME)

Answer 1

You can get rid of most of the arithmetic and just use:
SELECT COUNT(*) as "Total",
TO_CHAR(
TRUNC(DATE '1970-01-01' + INTERVAL '1' SECOND * INSERTION_TIME, 'HH'),
'DD/MM/YYYY HH24'
) as "Day"
FROM Records
WHERE ID=35
AND DATE '1970-01-01' + INTERVAL '1' SECOND * INSERTION_TIME >=sysdate - 4
GROUP BY
TRUNC(DATE '1970-01-01' + INTERVAL '1' SECOND * INSERTION_TIME, 'HH')
ORDER BY
TRUNC(DATE '1970-01-01' + INTERVAL '1' SECOND * INSERTION_TIME, 'HH')
Note: Epoch time is usually 1970-01-01 00:00:00 UTC. If your session time zone is not UTC then you may be calculating the epoch time incorrectly and would want to use timestamps instead:
SELECT COUNT(*) as "Total",
TO_CHAR(
TRUNC(
TIMESTAMP '1970-01-01 00:00:00 UTC' + INTERVAL '1' SECOND * INSERTION_TIME,
'HH'
),
'DD/MM/YYYY HH24'
) as "Day"
FROM Records
WHERE ID=35
AND TIMESTAMP '1970-01-01 00:00:00 UTC' + INTERVAL '1' SECOND * INSERTION_TIME
>=SYSTIMESTAMP - INTERVAL '4' DAY
GROUP BY
TRUNC(
TIMESTAMP '1970-01-01 00:00:00 UTC' + INTERVAL '1' SECOND * INSERTION_TIME,
'HH'
)
ORDER BY
TRUNC(
TIMESTAMP '1970-01-01 00:00:00 UTC' + INTERVAL '1' SECOND * INSERTION_TIME,
'HH'
)

Answer 2

Notice the behavior of trunc on your expression. It removes the hour component.
Test case with dbfiddle.uk:
Test case
The ungrouped SQL, with extra expression in select list:
select to_char(trunc(to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME),'DD/MM/YYYY HH24') as "Day"
, to_char( (to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME),'DD/MM/YYYY HH24') as "Day"
from Records
where ID = 35 and (INSERTION_TIME/86400) + to_date('01-01-1970 00:00:00','dd-mm-yyyy HH24:MI:SS') >= sysdate - 4
AND rownum < 6
order by (to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME)
;
The ungrouped result:
Now add the GROUP BY:
select COUNT(*) AS n
, to_char(trunc(to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME),'DD/MM/YYYY HH24') as "Day"
, to_char( (to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME),'DD/MM/YYYY HH24') as "Day"
from Records
where ID = 35 and (INSERTION_TIME/86400) + to_date('01-01-1970 00:00:00','dd-mm-yyyy HH24:MI:SS') >= sysdate - 4
group by (to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME)
order by (to_date('19700101 00', 'YYYYMMDD HH24') + ( 1 / 24 / 60 / 60 ) * INSERTION_TIME)
;
The grouped result:
To create a test case:
CREATE TABLE Records (
id int
, insertion_time int
);
INSERT INTO Records VALUES (35, 4011134567);
INSERT INTO Records VALUES (35, 4011134567);
INSERT INTO Records VALUES (35, 4011134567);
INSERT INTO Records VALUES (35, 4011134567);