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4 votes
4 votes
In a relation, if every attribute is prime but key may not be simple then the relation is in ______.

A. 1NF

B. 2NF

C. 3NF

D. BCNF

4 Answers

2 votes
2 votes
Let me explain...

For a functional dependency X --> Y on R

It is said to be in 3Nf if

1) x is a super key

2) or Y is aprime attribute

Now since according to question, every attribute is a prime attribute,thus for any fd's on the relatio the 2nd condition is fulfilled hence it is in 3NF
0 votes
0 votes

Relation R with only prime attributes: R in 3NF but may not BCNF


Example:

$R(A,B,C,D,E,F)$

$\left \{ AB\rightarrow C,C\rightarrow D, CD\rightarrow AE,DE\rightarrow F, F\rightarrow B\right \}$

$CK: AB,AF,ADE,C$


                                         $BCNF$                                     $3NF$

$AB\rightarrow C$                          $\checkmark$                                               $\checkmark$

$C\rightarrow D$                             $\checkmark$                                               $\checkmark$

$CD\rightarrow AE$                     $X$                                                $\checkmark$

$DE\rightarrow F$                        $X$                                                 $\checkmark$

$F\rightarrow B$                            $X$                                                 $\checkmark$

–1 votes
–1 votes
Answer is 3NF

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