UGC NET CSE | November 2017 | Part 3 | Question: 9

Question

If every non-key attribute is functionally dependent on the primary key, then the relation is in ________

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

Comments

Fully functionally dependent or partially functionally dependent ?

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yes , it  should be in 2NF.

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but fully or partially?

Answer 1

ANSWER MUST BE 2NF

EXPLANATION
2 NF – Every non-key attribute is fully functionally dependent on the primary key.
3 NF – No non-key attribute is transitively dependent on the primary key.

Answer 2

It Should be in 2NF.

According to the definition of 2NF and 3NF

2 NF – A relation R is in second normal form (2NF) if and only if it is in 1NF and every non-key attribute is fully dependent on the primary key.
Note that it does not put any restriction on the non-prime to non-prime attribute dependency. 

For Example
A--->B, B--->C , A--->C here A is key and relation is in  2NF.

Here A is Primary Key and every non key attributes i.e. B and C fully dependent on A

But here B--->C is also a functional dependency which voilate 3NF

3 NF – A relation R is in third normal form (3NF) if and only if it is in 2NF and every non-key attribute is non-transitively dependent on the primary key.

So Answer Should be 2NF

Answer 3

D. 4nf because it says about fd surely/primary key -ly hence there cann't be any partial fd also fd=> mvd.

Answer 4

Relation R(XYZ) with functional dependencies {X -> Y, Y -> Z, X -> Z}.
This relation is in 2NF but not in 3NF because of every non-key attribute(Y,Z) is transitively dependent on the primary key. Here {X} will be candidate key.Answer 2