Normalization

Question

 

Is the following relation in 3NF or not ?

Answer 1

lemme know if i m wrong.....

Comments

You are 100% correct.

Thanks.

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Hey, My teacher is saying that whenever we are given a table with values, then instead of making dependencies like you did, we have to make a diagrammatic representation (determinancy diagram) and then she says it would satisfy only 1NF and I don't believe that,  What is your opinion regarding this ? thanks.

This is what she is saying. (How can determinancy diagram give different answer ?)

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As of now , I didn't read any concept about Determinacy Diagram.

I try to check it...

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Given an instance of a relation, we cannot say a dependency exist- but we might be able to say that a dependency does not exist. So, the question is not really meaningful - what is the source?

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Arjun Sir, Here answer is 3 NF....

I completely agree with ur point " Given an instance of a relation, we cannot say a dependency exist- but we might be able to say that a dependency does not exist. "

But here in this question , what method I need to apply??

If I go on making FD then...

Student : S

Course : C

Instructor : I

Now relation R( S , C , I )

SC --> I

SI --> C

these 2 FD are possible 

 Both {SC} and {SI} are both are candidate keys,

All the attributes are prime

So, relation is 3 NF....

when will this point apply " Given an instance of a relation, we cannot say a dependency exist- but we might be able to say that a dependency does not exist. "???????

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Sir , this question is from my university exam. If you had to pick up the best choice which normal form do you think it is from ?

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@Akash Again that is wrong. When a Professor makes a question there won't be any ambiguity except in rare cases. But the question you pasted is clearly not made by a Professor. If we add the word "possible" and make it "highest possible normal form" then it makes sense. It might seem a simple typo but it is not. Because solving such questions will corrupt the knowledge and problem solving skills of GATE aspirants and when they see real GATE question they struggle. If we look  at GATE questions we can see how each word makes sense and correspond to some concepts.

Now as per your explanation why is it only 3NF and not BCNF?

@dremiclici :) I also studied in such University in India and as a University student you should know which answer gives mark. There is no way I can tell you the "thing" which gets you mark as I never studied in your university and I do not know Jyothish.

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Ok Arjun Sir , I got ur point .. Fine Thanx..