Partitioned Database and Choosing Subtables

I've got a ver 8.4.5 partitioned data base with records organized by US
state, so the partitions are set up by state. When I query this database
and include  the key field that tells postgres what partition you ,
everything works as I expect. It searches only the specified partition,
and it's fast . But that's only if I use a constant, like this:

SELECT lions,  tigers, bears FROM WildLife
WHERE state_pt = 'CO';

What I want to be able to do is put this key value in a table and PG
look in whatever partition the column specifies, like so:

SELECT lions,  tigers, bears, statecode FROM WildLife
WHERE state_pt = statecode;

However when I try anything other than a constant, it search EVERY
partition, sequentially, which is not what I want it to do. So is there
any way to specify the partition to search using a variable/column name?

--
*Bill Thoen*
GISnet - www.gisnet.com
303-786-9961