One of the kinds of reports that we get asked for periodically is 'Items that were owned by the library within a date range' -- essentially, the library want to know if the accession date is before the end of the date range, and the deletion date (if there is any) is after the beginning of the date range. The trouble is, I'm going to need to pull bibliographic data there as well, so I'm going to be looking at biblio and deletedbiblio as well. There's enough data that using unions is too slow, so I'm looking at coalesce statements. I'm just not sure how to make that all work together.