8.11

Consider the schemas for the table people, and the tables students and teachers, which were created under people, in Section 8.2.1.3. Give a relational schema in third normal form that represents the same information. Recall the constraints on subtables, and give all constraints that must be imposed on the relational schema so that every database instance of the relational schema can also be representated by an instance of the schema with inheritance.

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Take the schema:

tpeople(ID, name, address, degree, salary)

with the added constraint that at least one attribute of {degree , salary } is NULL.

The functional dependency that holds on tpeople:-

\(\{\) ID $} $ \(\{\) name, address, degree, salary \(\}\)