I've a document search page with three listboxes that allow multiple selections. They're:

Category A

Year

Category B

Only category A is mandatory, the others are optional parameters and might be empty.

Each document can belong to multiple options in Category A and multiple options Category B but each document only has one year associated with it.

I've kind of got this working through building up a dynamic SQL string but it's messy and I hate using it so I thought I'd ask here if anyone could see an easier way of doing this. An example of the kind of dynamic SQL query i end up with follows:

 select * 
from library
where libraryID in
(select distinct libraryID from categoryAdocs where categoryAdocID in (4))
or year in (2004)