ITEMS
=====
itemid catid name
------ ----- ----
1 1 Master & Commander DVD
2 1 Star Wars Episode II DVD
3 2 Red Hat Linux Bible
CATEGORIES
==========
catid name
----- ----
1 Movies
2 Books
PERIODS
=======
periodid name
-------- ----
1 Morning
2 Lunch
3 Afternoon
RESERVATIONS
============
rid date userid periodid itemid
--- ---- ------ -------- ------
1 02/02/05 1 1 1
2 02/02/05 2 2 1
3 02/02/05 1 3 1
...
I want to find all instances between two dates on which a specific item (or any item in a category) has not been reserved.