Human readable elapsed time between many days - sql

Question

I work with Oracle SQL and I have a table with 3 columns: Process, Start Date and End Date. I want to calculate the time duration for every process.
I used this query:
select
(enddate.date_value - startdate.date_value) as duration
from dual
and the result is in days.
For example: The start date is 30.3.2016 17:14:53 and the end date is 8.7.2016 14:51:21
When I use the query, the result is 99.90032407407407407407407407407407407407, but I want result like this:
3 months, 7 days, 21 hours, 36 minutes, 28 seconds.
How can I do that?

Answer 1

This complex query (specialy for DAY !!) :
To compute a correct Day I add Month and 12 * Year to the original date.
with dates as(
select
sysdate as d1,
sysdate-99.90032407407407407407407407407407407407-365 as d2
from
dual
),
dates_parts as (
SELECT
d1,
d2,
EXTRACT(YEAR FROM (d1 - d2) YEAR TO MONTH ) as Year,
EXTRACT(MONTH FROM (d1 - d2) YEAR TO MONTH ) as Month,
EXTRACT(DAY FROM (d1 - d2) DAY TO SECOND ) as Day,
EXTRACT(HOUR FROM cast(d1 as timestamp) - cast(d2 as timestamp)) as Hour,
EXTRACT(MINUTE FROM cast(d1 as timestamp) - cast(d2 as timestamp)) as Minute,
EXTRACT(SECOND FROM cast(d1 as timestamp) - cast(d2 as timestamp)) as Second
FROM dates
)
select
dates_parts.Year,
dates_parts.Month,
dates_parts.Day,
dates_parts.Hour,
dates_parts.Minute,
dates_parts.Second,
EXTRACT(DAY FROM (d1 - ADD_MONTHS(d2,Month+Year*12)) DAY TO SECOND ) as Day_Corrected
from
dates_parts
will produce the different date part :
| YEAR | MONTH | DAY | HOUR | MINUTE | SECOND | DAY_CORRECTED |
|------|-------|-----|------|--------|--------|---------------|
| 1 | 3 | 464 | 21 | 36 | 28 | 7 |

Answer 2

The difference between two DATE values is a number representing the number of days. You seem to want an interval, this can be done using TIMESTAMP values.
select cast(enddate as timestamp) - cast(startdate as timestamp)
from the_table
The result of subtracting a timestamp from a timestamp is an interval.
Formatting of an interval value is however quite tricky in Oracle. See e.g. format interval with to_char

Answer 3

Based on my previous answer you can create an Oracle function sinceHumanReadable:
exemple from https://momentjs.com/docs/#/plugins/preciserange/ produce the same result
moment("2014-01-01 12:00:00").preciseDiff("2015-03-04 16:05:06");
// 1 year 2 months 3 days 4 hours 5 minutes 6 seconds
http://sqlfiddle.com/#!4/d6783/1
create or replace FUNCTION sinceHumanReadable(start_date IN date,end_date IN date)
RETURN VARCHAR2
IS result VARCHAR2(255);
BEGIN
with
dates_parts as (
SELECT
EXTRACT(YEAR FROM (end_date - start_date) YEAR TO MONTH ) as Year,
EXTRACT(MONTH FROM (end_date - start_date) YEAR TO MONTH ) as Month,
EXTRACT(HOUR FROM cast(end_date as timestamp) - cast(start_date as timestamp)) as Hour,
EXTRACT(MINUTE FROM cast(end_date as timestamp) - cast(start_date as timestamp)) as Minute,
EXTRACT(SECOND FROM cast(end_date as timestamp) - cast(start_date as timestamp)) as Second
FROM dual
),
dates_parts_with_day as (
select
Year,Month,Hour,Minute,Second,
EXTRACT(DAY FROM (end_date - ADD_MONTHS(start_date,Month+Year*12)) DAY TO SECOND ) as Day
from dates_parts
)
select
decode(dates_parts_with_day.Year, 0,'', dates_parts_with_day.Year || ' years ' )||
decode(dates_parts_with_day.Month,0,'', dates_parts_with_day.Month || ' months ')||
decode(dates_parts_with_day.Day,0,'', dates_parts_with_day.Day || ' days ')||
decode(dates_parts_with_day.Hour,0,'', dates_parts_with_day.Hour || ' hours ')||
decode(dates_parts_with_day.Minute,0,'', dates_parts_with_day.Minute || ' minutes ')||
dates_parts_with_day.Second || ' seconds'
into result
from
dates_parts_with_day;
RETURN(result);
END sinceHumanReadable;
GO
The query
with dates as (
select sysdate-99.90032407407407407407407407407407407407 as d1,sysdate as d2 from dual
union all
select to_date('2016-03-30 17:14:53','yyyy-mm-dd hh24:mi:ss') as d1,to_date('2016-07-08 14:51:21','yyyy-mm-dd hh24:mi:ss') as d2 from dual
union all
select to_date('2014-01-01 12:00:00','yyyy-mm-dd hh24:mi:ss') as d1,to_date('2015-03-04 16:05:06','yyyy-mm-dd hh24:mi:ss') as d2 from dual
union all
select sysdate as d1,add_months(sysdate,35) as d2 from dual
union all
select sysdate as d1,sysdate as d2 from dual
)
select
d1,d2,
sinceHumanReadable(d1,d2) as since
from
dates;
will produce :
| D1 | D2 | SINCE |
|----------------------|----------------------|-----------------------------------------------------|
| 2017-07-19T17:50:00Z | 2017-10-27T15:26:28Z | 3 months 7 days 21 hours 36 minutes 28 seconds |
| 2016-03-30T17:14:53Z | 2016-07-08T14:51:21Z | 3 months 7 days 21 hours 36 minutes 28 seconds |
| 2014-01-01T12:00:00Z | 2015-03-04T16:05:06Z | 1 years 2 months 3 days 4 hours 5 minutes 6 seconds |
| 2017-10-27T15:26:28Z | 2020-09-27T15:26:28Z | 2 years 11 months 0 seconds |
| 2017-10-27T15:26:28Z | 2017-10-27T15:26:28Z | 0 seconds |