Composite Pkeys (Example)
Example: CS Dept View of SIS Database ERD:
The unique pkey which selects my section of OOAD in the Student Information System (SIS) Database is a composite of Dept, Course and Section number: 91.522.201.
(This is an’instance diagram’, not an ERD.
It shows field values in a single table row,
whereas an ERD shows only entity types.)