Functional Dependency (cont.) Exist in a relational schema as a constraint. Agree for all instances of the schema (t and u are any two tuples) AsBs+ We have functional L dependency like this A1A2.今B1B2… u Ift and!Then they u agree Why we call "functional" 5 must agree here here dependency?5 Functional Dependency (cont.) z Exist in a relational schema as a constraint. z Agree for all instances of the schema (t and u are any two tuples) A’s B’s If t and u agree here Then they must agree here t u We have functional dependency like this A1A2…ÆB1B2… Why we call “functional” dependency?