time.Since() with months and years

Question

I am trying to convert a timestamp like this:

2015-06-27T09:34:22+00:00

to a time since format so it would say like 9 months ago 1 day 2 ho

Answer 1

If you use PostgreSQL, you can easily get the result with age function.

Suppose you have two dates a and b.

Like icza said, be careful, a and b must be in the same time zone.

First, you can invoke age with two parameters, in your case date a and date b. This function return a interval type that contains years, months, weeks, days, hours, minutes, seconds, and milliseconds.

SELECT age('2016-03-31', '2016-06-30'); -- result is: -2 mons -30 days

The second possibilty is to use age function with one parameter. The result is a interval too but in this case, age subtract from current_date (at midnight). Suppose today is 2016/06/16:

SELECT age(timestamp '2016-06-30'); -- result is: -14 days

Note, timestamp keyword is needed to cast the date '2016-06-30'.

For more details, you can use date_part or directly extract function that return one specific field (years, months, days...).

SELECT date_part('month', age('2016-03-31', '2016-06-30')); --result is: -2
SELECT date_part('day',   age('2016-03-31', '2016-06-30')); --result is: -30

Full request:

SELECT  
    date_part('year', diff) as year
  , date_part('month', diff) as month
  , date_part('day', diff) as day
FROM (
  SELECT age(timestamp '2016-06-30') AS diff
) as qdiff;

-- result is: 
-- year month day
-- 0    0     -14

(with CTE - Common Table Expression):

WITH qdiff AS (
  SELECT age(timestamp '2016-06-30') AS diff
)
SELECT  
    date_part('year', diff) as year
  , date_part('month', diff) as month
  , date_part('day', diff) as day
FROM qdiff

-- result is: 
-- year month day
-- 0    0     -14

PostgreSQL documentation (current version): https://www.postgresql.org/docs/current/static/functions-datetime.html