PostgreSQL

Hi!

I'm using PostgreSQL for a search-web based database, and i saw a missing
function mostly found in DB2 and others, where, you can get results from
a query having a WHERE condition to exist or not in another SQL sentence .

In DB2 is:

SELECT field1, field2 FROM tab1 WHERE field1 IN ( select field3 from tab2 )
or
SELECT field1, field2 FROM tab1 where field1 NOT IN ( select field3 from tab2 )

PostgreSQL already has that, but only allows to return 1 result, ex:

SELECT field1, field2 FROM tab1 where field1 =
( select field 3 from tab2 where id=1 )

Would be great if that where added to the TODO as a future Feature.

Thanks in Advance.
Horaci Cuevas.