[Zope] ZCatalog, SQL database and PDF files

I just installed Zope2, and it's so great. ZCatalog almost does what I need to do in my current project. However, there's one thing that it couldn't do (or at least I don't know how it can be done) -- can ZCatalog be used to search a SQL database in addition to other objects in the Zope ODB? How about external files like PDF file? Python, SQL, Zope and even programming in general are all very new to me (I am a designer, not a programmer), so if someone knows how it can be done, please explain it in an easy to understand way (examples are the best!!!) Kam On Cheung