Self-Referencing

Hello,

I have a feeling this isn't going to make much sense, but I'm gonig to try
anyway.

What I'd like to do is be able to refer to an outer-SELECT from an
inner-SELECT. I hope this makes sense.

I need to be able to refer to the row that's being processed in a SELECT. I'm
going to use the idea of 'this' referring to the row that's currently being
processed. Here's the example of what I'd like:

SELECT
building_id,
num_buildings,
(
SELECT count( building_id )
FROM building_portals
WHERE building_id = THIS.building_id
)
FROM buildings;

Am I making things too complicated, and if so will somebody *PLEASE* tell me
the easier way to do this. Thanks.

-- Dave