Question

Which of the following is used for discovering superky Yanitiniz: Extraneous attribute test O BCNF rest Attribute closure test 3NF test

Answer 1

(a)
The word extraneous means irrelevant. Extraneous attribute test is used to check whether the given set of functional dependencies contain any irrelevant funcional dependencies or not so that when we remove such dependencies it doesn't affect the closure of the set of functional dependencies. It has nothing to do with finding superkeys. Therefore this is not the answer.

(b)
BCNF test is used to check whether the given relation doen't contain any redundant entries. It implements the concept of superkeys to find such functional dependencies which can cause redundancy. This also has nothing to do with discovering superkeys.

(c)
Attribute closure test is the test which is used to find the superkeys. If the attribute closure of a set of attributes contains all the attributes in a relation, then those set of attributes is considered as a superkey.
Therefore this is the correct answer.

(d)
3NF test is another test which is used to reduce redundancy. This is less stricter that BCNF. It also uses the concept of superkey, but cannot be used to find any.

So the correct answer is Attribute closure test.