Re: practice test question...

MadG wrote:
>
> I have a test Friday in my Database Systems class. The prof gave us
> a practise test with this question. He's not taking anything up and
> I'm really stuck. I've gotten as far as what's included, but
> everytime I try to expand the answer it looks wrong.
>
> Could you help?

Yes, but I am only going to tell you what I think your teacher would have said if he was in a more helpful mood. :-)

> ---- 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