Calculate difference between dates - Postgres

Question

I have a requirement to calculate the number of days from 3 different dates. I need to run the logic to get an integer value from below pseudo logic.

(future_date_1 - future_date_2) - Today()

How to achieve this in PostgreSQL?

Answer 1

In order to achieve the date difference in days,

SELECT DATE_PART('day', '2011-12-31 01:00:00'::timestamp - '2011-12-29 23:00:00'::timestamp);

OR

this also works pretty well

select '2015-01-12'::date - '2015-01-01'::date;

Now, you only need to use this logic and satisfy your requirement.