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

Okay, so you've got a numeric(18) column containing numbers like 20150118. You can convert that to a date like:

to_date(your_date_column::text, 'YYYYMMDD')

From a date, you can grab the last day of the month like:

(date_trunc('month', your_date_column) + 
    interval '1 month' - interval '1 day')::date;

Combined, you'd get:

select  (date_trunc('month', to_date(act_dt::text, 'YYYYMMDD')) + 
           interval '1 month' - interval '1 day')::date
from    YourTable;

Example at SQL Fiddle.