ISRO2020-50

Question

If every non-key attribute functionally dependent on the primary key, then the relation will be in

• A. First normal form
• B. Second normal form
• C. Third normal form
• D. Fourth Normal form

Comments

I will claim this question..

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Yes, it is not mentioned whether it is full or partial functional dependency.

The language of question is very poor as it can vary with different interpretations from $1-NF$, $2-NF$, and $3-NF$.

And if I don't presume anything then according to me $\mathbf{1-NF}$ is the only sure shot answer.

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R: {X→Y,  Y→Z,  X→Z}

In above relation,  in FD Y→Z, Z is clearly Non key attribute and It is NOT dependent on Primary key Because Primary key is X.  So, Y→Z is not correct FD for given statement. Answer has to be 3NF.

Answer 1

It is assumed that no partial dependency and transitive dependency exist in the given question, so it in 3NF.

Answer 2

Since all the non-prime attributes are FULLY dependent functionally on the Primary Key, so it in 2NF.

Hence the option B is correct.

Answer 3

Answer :- C

Let's say A->B  . in the definition of 3NF , A is superkey/superset of B . or

 

no non-prime attribute is functionally dependent on other non-prime attribute .

 

in the question they said : every non-key attribute functionally dependent on the primary key

 

it means , from the second definition we can say that if A is prime attribute  and B is non-prime attribute , then this satisfy 3NF property 

Answer 4

In my view it is in 3NF because for 1NF only atomic value, 2NF there should be no partial dependency meaning no non-prime key should be dependent of proper subset of candidate key and in 3NF there should not be any transistive dependencies of non prime attributes.