Use of Functional Dependencies We use functional dependencies to: test relations to see if they are legal under a given set of functional dependencies. If a relation r is legal under a set F of functional dependencies,we say that rsatisfies F. specify constraints on the set of legal relations We say that F holds on R if all legal relations on R satisfy the set of functional dependencies F. Note:A specific instance of a relation schema may satisfy a functional dependency even if the functional dependency does not hold on all legal instances. For example,a specific instance of instructor may,by chance,satisfy name->ID. Database System Concepts-6th Edition 8.14 @Silberschatz,Korth and SudarshanDatabase System Concepts - 6 8.14 ©Silberschatz, Korth and Sudarshan th Edition Use of Functional Dependencies We use functional dependencies to: test relations to see if they are legal under a given set of functional dependencies.  If a relation r is legal under a set F of functional dependencies, we say that r satisfies F. specify constraints on the set of legal relations  We say that F holds on R if all legal relations on R satisfy the set of functional dependencies F. Note: A specific instance of a relation schema may satisfy a functional dependency even if the functional dependency does not hold on all legal instances. For example, a specific instance of instructor may, by chance, satisfy name → ID