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Re: Normal Forms and BCNF

From: Jan Hidders <hidders_at_REMOVE.THIS.uia.ua.ac.be>
Date: 13 Nov 2002 18:14:05 +0100
Message-ID: <3dd2885d$1@news.uia.ac.be>


Kasp wrote:
>hidders_at_REMOVE.THIS.uia.ua.ac.be (Jan Hidders) wrote in message
>news:<3dd16a5e$1_at_news.uia.ac.be>...
>> Kasp wrote:
>> >Hi,
>> >I am a little confused with Normal Forms and BCNF.
>> >I have some relations and I am trying to determine it's normal form. I
>> >also need to decompose it to BCNF forms...Any help would be
>> >appreciated.
>>
>> We don't just simply give answers here because that way you wouldn't learn
>> anything. But if you tell us what you do and do not understand of the
>> definitions of the normal forms and the procedures to obtain them, we will
>> be glad to give you some hints about what it is your instructor tried to
>> tell you.
>
>I have read the book. But I can't get started on even one question.
>How do I go about it?
>
>I find it pretty easy to understand with book examples...but A<B<C<D
>make it cryptic. Can you please explain how to do any one?

That wouldn't be very instructive.

Here are the steps that need to be performed: 1. From the FDs you have to derive the candidate keys. 2. Then you check if given these derived candidate keys there is a

   dependency that violates the 2NF.
3. If it does then you split this dependency off into another relation. 4. You repeat 2. and 3. for all the resulting relations until there are no more

   violations of 2NF.

After this you repeat 2, 3 and 4 for subsequently the 3NF and BCNF.

Let's start with step 1. So what does the book say about deriving candidate keys? Does it tell you what they are? Does it tell you how to derive them? Received on Wed Nov 13 2002 - 11:14:05 CST

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