How to get the date difference between start date and end date in oracle as hours and minutes - oracle

Question

I have a scenario in which for example,my start_date ='12-SEP-2018 00:01:00' and End_date ='13-SEP-2018 14:55:00' . The difference between the 2 dates must be found out in Hours and minutes like'12:20'. This must be achieved in oracle database. I tried using the following logic :
SELECT
24 * (to_date('2009-07-07 22:00', 'YYYY-MM-DD hh24:mi') - to_date(
'2009-07-07 19:30', 'YYYY-MM-DD hh24:mi')) diff_hours
FROM
dual;
I was able to get the hour difference but unable to get minutes along with it.

Answer 1

CREATE TABLE table_name ( start_date DATE, end_date DATE );
INSERT INTO table_name VALUES ( TIMESTAMP '2009-07-07 19:30:00', TIMESTAMP '2009-07-07 22:00:00' );
Then you can subtract one from the other and cast it to a DAY TO SECOND interval and then just EXTRACT the component parts of the time:
SELECT EXTRACT( DAY FROM difference ) AS days,
EXTRACT( HOUR FROM difference ) AS hours,
EXTRACT( MINUTE FROM difference ) AS minutes,
EXTRACT( SECOND FROM difference ) AS seconds
FROM (
SELECT ( end_date - start_date ) DAY TO SECOND AS difference
FROM table_name
);
Outputs:
DAYS | HOURS | MINUTES | SECONDS
---: | ----: | ------: | ------:
0 | 2 | 30 | 0
or you can use arithmetic to calculate the values:
SELECT TRUNC( 24 * ( end_date - start_date ) ) AS hours,
TRUNC( MOD( 24 * 60 * ( end_date - start_date ), 60 ) ) AS minutes,
ROUND( MOD( 24 * 60 * 60 * ( end_date - start_date ), 60 ) ) AS seconds
FROM table_name;
which outputs:
HOURS | MINUTES | SECONDS
----: | ------: | ------:
2 | 30 | 0
db<>fiddle here

Answer 2

Since you want a string value, an alternative based on your query attempt is to add the difference between your two date values (which is a numeric value, the number of days between them, including fractional days) to an arbitrary fixed date; and then convert the result of that to a string:
SELECT to_char(date '0001-01-01'
+ (to_date('2009-07-07 22:00', 'YYYY-MM-DD hh24:mi') - to_date( '2009-07-07 19:30', 'YYYY-MM-DD hh24:mi')),
'HH24:MI') as diff
FROM dual;
DIFF
-----
02:30
If the difference can exceed 24 hours then you need to decide how to report that; if you want to include days as a separate figure then you can still use this approach, but need to subtract one (if your fixed date is the first) from the difference before formatting as a string:
SELECT to_char(date '0001-01-01'
+ (to_date('2009-07-08 22:00', 'YYYY-MM-DD hh24:mi') - to_date( '2009-07-07 19:30', 'YYYY-MM-DD hh24:mi'))
- 1,
'DDD:HH24:MI') as diff
FROM dual;
DIFF
---------
001:02:30
If you want the 'hours' value to be higher instead - e.g. '26:30' in this example - then it gets rather more complicated; I see #MTO has added the 'arithmetic' approach already so I won't repeat that. But then might be better off going down the extract() route (which you should consider anyway as it's more flexible and elegant...)