I have to agree with @ChanChan on reading the ical spec for how to store these things. There is no easy way to handle recurrences, especially ones that have exceptions. I've built and rebuilt and rebuilt a database to handle this, and I keep coming back to ical.
It's not a bad idea to create a subordinate table, depending on use cases. The algorithm for calculating exactly when occurrences . . . um, occur . . . can indeed be quite complex. There's no getting away from running it, but it's worth considering caching the results.
