Using iPhoto without copying images?

I got a Mac recently and would love to try iPhoto, but I have 15000+ images arranged in folders, which are referenced by image file path in a database. I don't want iPhoto to copy all the photos, and I don't want my database references to get ruined.

Any advice?

iPhoto has a preference for controlling whether imported photos are copied from their original locations into the iPhoto library folder, or left where they are. Launch iPhoto, select "Preferences…" from the "iPhoto" menu, click the "Advanced" toolbar icon, and uncheck the checkbox at the top of the "Importing" section to give it a try: