0 0 votes prime attributes are any attribute that are members of candidate key cant we say that members of SK are also prime attributes? Databases + – sudsho 2.1k views answer comment Share Follow Print 0 reply Please log in or register to add a comment.
Best answer 1 1 vote 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. Habibkhan answered Oct 9, 2016 • selected Oct 9, 2016 by sudsho Habibkhan comment Share Follow See all 8 Comments 8 8 Comments reply sudsho commented Oct 9, 2016 reply Follow flag thanks... one more thing if we have a relation ABCD and AC is the key here FDs are AC->B AD->B is AD->B a transitive dependency? 0 0 replyShare Habibkhan commented Oct 9, 2016 reply Follow flag But according to your given FDs ,ACD is a candidate key not AC only 0 0 replyShare sudsho commented Oct 9, 2016 reply Follow flag yea sorry mistake...let it AC->BD....i just wanna know if we have a CK like AC and a FD like AD-> something what it would be then? 0 0 replyShare Habibkhan commented Oct 9, 2016 reply Follow flag See then the left hand side i.e AD is a combination of prime and non prime.Hence it is not a transitive dependency 0 0 replyShare sudsho commented Oct 9, 2016 reply Follow flag then AD is not a partial dependency also right? so what will be the highest normal form for this relation? 0 0 replyShare Habibkhan commented Oct 9, 2016 reply Follow flag 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 1 1 replyShare sudsho commented Oct 9, 2016 reply Follow flag ohk thankyou :) 0 0 replyShare amolagrawal commented Dec 31, 2016 reply Follow flag 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. 0 0 replyShare Please log in or register to add a comment.
1 1 vote 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 Shubham Pandey 2 answered Oct 9, 2016 Shubham Pandey 2 comment Share Follow See all 5 Comments 5 5 Comments reply Show 2 previous comments sudsho commented Oct 9, 2016 reply Follow flag 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? 0 0 replyShare Shubham Pandey 2 commented Oct 9, 2016 reply Follow flag No, https://en.wikipedia.org/wiki/Transitive_dependency 0 0 replyShare sudsho commented Oct 9, 2016 reply Follow flag then what is this? what will be the highest normal form for such relation? 0 0 replyShare Please log in or register to add a comment.
