For a database relation R(A, B, C, D) where the domains of A, B, C and D include only atomic values, only the following functional dependencies and those that can be inferred from them are :

A → C

B → D

The relation R is in _______.**(A)** First normal form but not in second normal form.**(B)** Both in first normal form as well as in second normal form.**(C)** Second normal form but not in third normal form.**(D)** Both in second normal form as well as in third normal form.**Answer:** **(A)****Explanation:** A relation is in first normal form if every attribute in that relation is single valued attribute. It is in 1NF.

{A,B} are prime attribtes and {C,D} are non-prime attribute.

A^{+} = {A,C}

B^{+} = {B,D}

{A,B}^{+} = {A,B,C,D} so AB is the key.

But A^{+} = {A,C}

B^{+} = {B,D} makes it partial dependency.

So, this relation is not in 2NF.

So, option (A) is correct.

Quiz of this Question

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