Re: practise test.. Does This Look Right?

Okay, from your original post here's what appears to be the problem description:
<begin>
Keep track of textbook features to be evaluated (content coverage, ease of reading, exercises, cost), the weights (1-3) associated with each of these features and the evaluation number (1-10) scored for each feature of a particular textbook.

There is a requirement to identify the textbooks being evaluated for different subject areas (example: systems analysis and design; database systems; C++ programming)
<end>

How about this.

Entities:

   Textbook
   Textbook Feature
   Textbook Evaluation
   Textbook Feature Evaluation

Relationships:

    Textbook (1) owns Textbook Feature (M)     Textbook (1) owns Textbook Evaluation (M)     Textbook Evaluation (1) owns Textbook Feature Evaluation(M)     Textbook Feature (1) owns Textbook Feature Evaluation (M)

Weight is an attribute of Textbook Feature. Subject Area is an attribute of Textbook. Evaluation Number is an attribute of Textbook Feature Evaluation.

Textbook Feature Evaluation is an intersection, a.k.a. junction, between Textbook Evaluation and Textbook Feature.

Apparently Publisher, Affiliate, and Supplement are irrelevant. And what the heck is this "repeating group" stuff? And what do you mean by "I've gotten as far as what's included, but everytime I try to expand the answer it looks wrong?"
Either you're slacking or your prof is a knucklehead. - cb

MadG <patrick4133_at_hotmail.com> wrote in message news:MSxr6.30402$p66.9874881_at_news3.rdc1.on.home.com...
> I'm still a bit stuck, and I'm sorry if my question seems lame
> for this newsgroup. If my question is unwelcome please tell me,
> and I'll stop.
>
>
> I didn't make an entity for the subject area
> because I thought that this would work out better.
>
> However, I am not at all sure about the Supplement entity.
> I don't like the feel of it and don't
> know what other options I have.
> The supplement is not required, and there may be many to each ISBN.
>
> The ERD would be:
>
> TEXTBOOK(1) contains SUPPLEMENT(M)
> TEXTBOOK(1) is affiliated to AFFILIATE(1)
> TEXTBOOK(1) gets EVALUATE(1)
> EVALUATE(M) is worth WEIGHT(1)
> AFFILIATE(1) is published by PUBLISHER(M)
> {I need better verbs..}
>
> MY PROGRESS IN NORMALIZATION ( is it 3nf yet? )
> ----
>
> TEXTBOOK ( ISBN[PK], BOOKNAME, AUTHOR, AFF_NUM[FK TO AFFILIATE], YEAR,
> COST )
>
> PUBLISHER ( PUB_NUM[PK], PUB_NUM, CONTACT, WEBSITE, LAST_CONTACT )
>
> AFFILIATE ( AFF_NUM[PK], PUB_NUM[FK TO PUBLISHER], AFF_NAME )
>
> SUPPLEMENT ( ISBN[ISBN FK TO TEXTBOOK], SUPPLEMENT [COMPOSITE PK] )
>
> EVALUATE ( ISBN, BOOKNAME, SUBJECT[FK TO WEIGHT], CONTENT, EASE_READ,
> EXERCISES, COST )
> BOOKNAME WOULD HAVE BEEN A CANDIDATE KEY, HOWEVER THE CHANCE OF INPUT
 ERROR
> IS TOO GREAT.
>
> WEIGHT ( SUBJECT, CONTENT_W, EASE_READ_W, EXERCISES_W, COST_W )
>
>
> ##################
> ###################
> forwarded
>
>
> > ---- Entites
> > TEXTBOOK (ISBN[PRIMARY KEY], BOOKNAME, AUTHOR, AFF_NUM[FORIEGN KEY
> > --A.TABLE], YEAR. COST (SUPPLEMENT)[REPEATING GROUP])
> >
> > PUBLISHER (PUB_NUM[PRIMARY KEY], PUB_NAME, CONTACT, WEBSITE,
 LAST_CONTACT)
> >
> > AFFILIATE (AFF_NUM[PRIMARY KEY], PUB_NUM[FOREIGN KEY -P.TABLE],
 AFF_NAME)
> >
> > ----
> >
> > Keep track of textbook features to be evaluated (content coverage,
> > ease of reading, exercises, cost), the weights (1-3) associated with
> > each of these features and the evaluation number (1-10) scored for
> > each feature of a particular textbook.
>
> Think of the entity 'Evaluation'.
>
> Important questions: What attributes belong to an Evaluation? What
> identifies an Evaluation? Is the relationship between Evaluation and
> Textbook a one-to-one, one-to-many, many-to-one, or a many-to-many
> relationship?
>
> > There is a requirement to identify the textbooks being evaluated for
> > different subject areas (example: systems analysis and design;
> > database systems; C++ programming)
>
> Think of the entity 'Subject area' and ask the same questions. What
> attributes are there? How is a subject area identified. What type of
> relationship does it have with Book?
>
> > I don not know how to take care of the repeating group. I had
> > thought that perhaps I should create an entity SUPPLEMENT but from
> > there I get stuck as to what to include.
>
> You have to include of course the information in the repeating group
> itself, but also something that relates these records to the original
> records that they belonged to. What foreign key could do that?
>
> Good luck,
>
> --
> Jan Hidders
>
>
Received on Wed Mar 14 2001 - 08:03:41 CET