Is it necessary to fill IDs when relationships are established? (database design)
I'd like to track events. These have a date and a description and they are always associated with an instructor. Additionally, they can be associated with a client. The design looks like this:
Events >--- Instructors
Instructors: pkInstructorID = Events: fkInstructorID
Clients: pkClientID = Events: fkClientID
Considering these relationships is it okay to simply leave fkClientID empty for those events where no client is involved? Or is it necessary to fill IDs when relationships are established?