Practice Problems in DBMS

Question

I have a small doubt regarding, determining the highest normal form category, for 2NF as per the rule we know, that, for the given candidate key, no proper subset of candidate key should determine non prime key.

Consider the example here, for Relation R(A,B,C,D,E,F). FD’s is {AB → CD , CD → EF, BC → DEF, D → B and CE → F}

so from FD we know that: AB is an candidate key, but my question is BC → DEF is violating 2NF principle as B is part of candidate key, so why above Relation is consider as in 2NF.

Thankyou very much in advance for clearing my doubt. #DBMS #Gate

Answer 1

B is the proper subset of BC, not AB. Hence we cannot say there is a case of partial dependency.