DBMS

Question

prime attribute appears in some candidate key???pls explain how??

Answer 1

R(ABCDE)

AB-> CD

C->B

D->E

 

candidate key  are AB and AC.

then A, B, C are prime attribute.. here B come in one candidate key not in both But also a prime attribute.

SO any attribute which are in any candidate key are prime attribute.

Comments

Is prime attribute appears in all ck???

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no prime attribute is one who apear in any candidate key.. see above i explain it.. B is appear only in one candidate key.. 

Is prime attribute appears in all ck

but according to this statemnt only A and C are prime attribute but B is not.

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ok got it

Answer 2

It is other way around. Whichever attribute that appears in some candidate key is called a prime attribute.