That works - Thanks!!!

The supertype table Persons has several "child" tables containing information (e.g., contact information) that applies to all "persons" -- both employees and non-employees.

However, subtype table Employees has several...

Thanks....I think this is basically what I ended up with --- A table "Activities" (which contains ActivityID, ActivityDate, Author, Comments, etc). There are 2 child tables --- OrderActivities and...

Also, there MAY be a need to examine ALL activities (i.e, including all orders, invoices, etc.). We may add a few more columns to the Activities table(s) --- "ActionsRequired"...

I considered creating multiple activity tables, but a database with 10+ virtually identical tables (except for a FK to the parent table) just doesn't seem to be normalized.