How to ensure a "unique" related record?
I have a lectures table and a faculty table. There is a third table used to assign the faculty to the lecture to allow for more than one faculty to be assigned to each lecture. However, I need to make one of the faculty the "primary" contact for the lecture. While it would be OK to have many "secondary" faculty assigned to each lecture, I want to prevent anyone from inadvertently making more than one primary assignment. Any suggestions as to how to enforce this?