What you really want to do is buy a copy of the new edition: Philip and Alex's Guide to Web Publishing (which has its own how to get a hardcopy page).
Database Backed Web Sites is out of print. Macmillan sold all the copies that they printed.
Note that "out of print" does not mean unavailable. If you send email to firstname.lastname@example.org (the MIT Press Bookstore), you can get an autographed copy. They bought more than 200 copies in September 1998 so I doubt that they'll run out anytime soon.
Amazon.com sold quite a few copies and may have clever ways of getting a physical book. The amazon page has lots of fun reader reviews so it is worth checking out anyway.
If you speak German, you can get the German translation by Olaf Borkner-Delcarlo. It didn't come out until May 1998 and hence should be available for some time.