How to get the last day of month in postgres?

Question

How to find the last day os the month in postgres? I have a date columns stored as numeric(18) in the format(YYYYMMDD) I am trying it to make it date using

Answer 1

For anybody coming to this question looking for the Postgres way to do this (not using Redshift), here's how you'd do it:

SELECT (date_trunc('month', '2017-01-05'::date) + interval '1 month' - interval '1 day')::date
AS end_of_month;

Replacing the '2017-01-05' with whatever date you want to use. You can make this into a function like this:

create function end_of_month(date)
returns date as
$$
select (date_trunc('month', $1) + interval '1 month' - interval '1 day')::date;
$$ language 'sql'
immutable strict;