Question

prime attributes are any attribute that are members of candidate key
cant we say that members of SK are also prime attributes?

Answer 1

No its not true..

Suppose a relation R(ABCD) and let AB be the candidate key.

Then the prime attributes are : A,B

But superkey can be either of AB , ABC , ABD , ABCD

So lets consider a superkey : ABC

so C is also a member of ABC but C is not a prime attribute as C is not part of AB :)

I hope u got the point.

Comments

Since there is a dependency AD --> B and for 3NF we require either AD is a key which is not the case nor B is a prime attribute .So it is not in 3NF.

But since AD is not a proper subset of AC so it is in 2NF.Had it been a proper subset say C and it were derive a non prime attribute say B then it would be a partial dependency

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ohk thankyou :)

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Considering same example...

Correct me if i my understanding is wrong. AC -> B is not a partial dependency since AC is not the proper subset of candidate key, it is a candidate key. Had it been C -> B or A -> B it would be partial dependency.

Thanks in advance.

Answer 2

No, we  cant say  that members of SK are also prime attributes?

Set of all attribute is super key

if you take prime attribute as any attribute that are members of Super key 

Then all attribute became prime attribute

Comments

ohk thnks...one more thing

if suppose AC is a candidae key for any relation
and we have a FD as

AD->B

then is this a transitive dependency?

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No,

https://en.wikipedia.org/wiki/Transitive_dependency

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then what is this?
what will be the highest normal form for such relation?