I see 2 ways how you can do it:
1. migrate this database to any Radius server and connect it to Ruckus system in standart way using Radius. It is easy enough to Export and import db but may be problematic, if your db is integrated with any other services and have to stay. Anyway, it is better to move to standart based solution, if possible.
2. Make integration of the Guest portal / WISPR with this DB. Possible, not very secure, as it will use web-authentication, but for university students will probably be enough. Integration approach is described in Ruckus manual, but it will take some work.
Hope it helps,