N天前的日期

Question

Is there less verbose way to get date N days ago?

select ('today'::date -'20 days'::interval)::date;
    date
------------
 2018-07-10

Answer 1

https://www.postgresql.org/docs/current/static/functions-datetime.html has example (the very first date + integer , so you can omit interval and date casts:

db=# select current_date -20;
  ?column?
------------
 2018-07-10
(1 row)

Answer 2

I think the "correct" way in Postgres is:

select current_date - interval '20 day'

Although you can use - 20 as a shorthand for - interval '20 day' , I strongly recommend that you use the full interval form for clarity.