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 attributes 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.
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Last Updated :
21 Dec, 2021
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