Function Temp Table Woes

Hello,

I'm a newbie to plpgsql functions so any help I can
get would be appreciated. I have a little bit of a
history with MS SQL Server 2000, so this may be where
I'm messed up ;)

The Goal: Return a set of records from one table based
on entries in a temporary table. I'd expect this to be
a commonly requested functionality. After reading the
docs, support lists and googling, I haven't come up
with a clean solution. My query is at the end of this
post.

I've come to the conclusion that returning a REFCURSOR
is the best approach, but I will take other
suggestions. My current issue is that the temp table
(tt_occ_units) is not being dropped after commit. The
second calling of this function produces the 'relation
already exists' error.

I've learned that there is an implicit transaction
around every function and I was hoping that
transaction would force the commit and drop the table.
That tells me that the table shouldn't be there if I
immediately call it again. Otherwise, I am calling
this function using SQL similar to: BEGIN; SELECT
sUnitsByOccStatus('c', FALSE, '08/07/2006'); FETCH ALL
IN c; COMMIT;

Note that I am actually making this call from PHP.
But, after I get over this hurdle, I'm sure I can make
it work from there.

Any thoughts?
Thanks in advance.

-Chad

--Current function text
CREATE OR REPLACE FUNCTION sUnitsByOccStatus (cur
REFCURSOR, occupied BOOLEAN, refDate DATE) RETURNS
REFCURSOR
AS $$
BEGIN
CREATE TEMP TABLE tt_occ_units (unit_id INTEGER)
ON COMMIT DROP;
-- Get ids for all available units
SELECT u.id INTO tt_occ_units
FROM tbl_unit u
INNER JOIN tbl_tenant_unit tu ON u.id =
tu.unit_id
INNER JOIN tbl_rent r ON tu.rent_id = r.id
WHERE r.date_start < refDate AND r.date_end
> refDate;

-- Return tbl_unit records for avail or not
avail depending on what the caller wants.
IF occupied THEN
OPEN cur FOR SELECT u.* FROM tbl_unit u
WHERE u.id IN (select unit_id from
tt_occ_units);
ELSE
OPEN cur FOR SELECT u.* FROM tbl_unit u
WHERE u.id NOT IN (select unit_id from
tt_occ_units);
END IF; -- IF
RETURN cur;
END;
$$ LANGUAGE plpgsql STRICT VOLATILE;

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