PostgreSQL: How to return rows with respect to a found row (relative results)?

Question

Forgive my example if it does not make sense. I\'m going to try with a simplified one to encourage more participation.

Consider a table like the following:

Answer 1

create table foo (dt date);
insert into foo values
('2012-12-01'),
('2012-08-01'),
('2012-07-01'),
('2012-06-01'),
('2012-05-01'),
('2012-04-01'),
('2012-03-01'),
('2012-02-01'),
('2012-01-01'),
('1997-01-01'),
('2012-09-01'),
('2012-10-01'),
('2012-11-01'),
('2013-01-01')
;

select dt
from (
(
    select dt
    from foo
    where dt <= current_date
    order by dt desc
    limit 4
)
union all
(
    select dt
    from foo
    where dt > current_date
    order by dt
    limit 7
)) s
order by dt
;
     dt     
------------
 2012-03-01
 2012-04-01
 2012-05-01
 2012-06-01
 2012-07-01
 2012-08-01
 2012-09-01
 2012-10-01
 2012-11-01
 2012-12-01
 2013-01-01
(11 rows)