To simplify query-writing, I've replaced all instances of NULL with 0 in the following fields documents.doc_loc_id
documents.doc_credit_id
documents.doc_archive_id
documents.doc_coll_id
I've added a record to each of these tables with the id of 0 and text values of [none]
locations
credits
archives
collections
I now get the correct number of records back from my searches.
