Ace DBMS Textbook

Question

Consider a relation R(A,B,C,D,E,F,G) and the following functional dependencies: (B->D, D->E, AB->C, AE-F, C -> A, F -> G } and choose the correct option:

(A) Only A and B are prime attributes

(D) Only A, B and C are prime attributes

(B) Only B and C are prime attributes

(C) Only A, B and F are prime attributes

Answer 1

For given relation first will identify candidate keys –

{AB}+ → {A, B, D, E, C, F, G }

{BC}+ → { B, C, A, D, E, F, G }

 

prime attributes are – A, B and C

Comments

So basically, prime attribute consists of the attributes which combinely forms super keys, right?

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Formal Definition given in Navathe –  An attribute of relation schema R is called a prime attribute of R if it is a member of some candidate key of R. An attribute is called nonprime if it is not a prime attribute — that is, if it is not a member of any candidate key.

Answer 2

500. only a,b,c are prime atribute