ISRO cs 2020

Question

Given R(ABCD) FD's={A->C,B->D}. Is this in 3NF?If NO why?

Answer 1

FD's={A->C,B->D}

$AB^{+}$ ={A,B,C,D}

So Candidate key is AB so A and B are prime attributes and C and D are non-prime attributes.

here in given FD

A->C

B->D

 

which means part of Candidate key determining non-key attribute or we can say partial attribute of key determining non key  so it is not in 2NF hence not in 3 NF also.