Question

Database

1. Let A4, A5, and A6 be attributes in a relation R. If both of these functional dependencies hold: A4 → A5 and A5 → A6, then A4 → A6holds, because of the _________ rule.

2. The fact that the value of a foreign key attribute must exist in another set of one or more key attributes in another table, is called a(n) __________.

3. Any set of attributes that allows us to identify unique rows (tuples) in a given relation are known as super keys. Out of these super keys we can always choose a proper subset among these which can be used as a _____ key. Such keys are known as _____ keys. If there is a combination of two or more attributes which is being used as the primary key then we call it as a _____ key.

Answer 1

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