basic_dates.sql

select
    date_trunc('year', '2013-04-05'::date) as year
    , date_trunc('month', '2013-04-05'::date) as month
    , date_trunc('day', '2013-04-05'::date) as day;
--          year          |         month          |          day           
--------------------------+------------------------+------------------------
-- 2013-01-01 00:00:00-05 | 2013-04-01 00:00:00-04 | 2013-04-05 00:00:00-04
select
    to_char('2013-04-05'::date, 'YYYY') as year
    , to_char('2013-04-05'::date, 'MM-YYYY') as month
    , to_char('2013-04-05'::date, 'YYYYMMDD') as day;
-- year |  month  |   day    
--------+---------+----------
-- 2013 | 04-2013 | 20130405
 
select
    to_timestamp(1365560673);
--      to_timestamp      
------------------------
-- 2013-04-09 22:24:33-04

select date_part('day', '2013-04-05'::date);
-- date_part 
-------------
--         5

select date_part('second', to_timestamp(1365560673));
 --date_part 
-------------
--        33