Re: Video rental shop

why not shop ->> copy, instead of shop ->> titles

On 3 Aug 2001 03:47:58 -0700, jreesmf_at_mac.com (Joel Rees) wrote:

>"mgkiourt" <mgkiourt_at_otenet.gr> wrote in message news:<9k40k2$2bn2$1@ulysses.noc.ntua.gr>...
>> The video rental shop classifies movie titles according to their type:
>> classical,western,new release.
>> Each type cotains many possibble titles and most titles within a type are
>> available in multiple copies.
>> Movies classified as new releases are reclassified to an appropriate type
>> after they have been in stock for thirty days.
>> Any help?
>> Thanks.Mike
>
>Okay, logical relationships:
>
>shop ->> titles
>
>title -> genre
>
>genre ->> title
>
>copy -> title
>
>title ->> copy
>
>copy -> title
>
>Approach new titles in one of two ways. Either make new titles a genre
>with an action that raises a flag for hand re-classification in thirty
>days, or make a separate new title relation that only keeps titles for
>thirty days.
>
>Making new title a genre may reduce the amount of machinery you have
>to build, and waiting 30 days to assign the regular genre would give
>you time to get opinions on the assignment of genre (as in a flick
>that looks like a western but turns out to be an American gothic
>romance).
>
>The new title relation would look like
>
>title -> age
>
>age ->> title
>
>and the advantage here would be to be able to assign the genre when
>the title is entered in the database, and have an action clear the new
>title flag automatically.
>
>You might also have two genre, a publisher's classification and a
>customer's classification:
>
>title -> pub_genre
>
>pub_genre ->> title
>
>title -> cust_genre
>
>cust_genre ->> title
>
>And new title be a possible value for cust_genre, with an action to
>set a flag for manual re-classification at thirty days.
>
>Shoot, if you really wanted to, you could have arbitrarily many genre,
>but why bother?
>
>And if I've just done your homework assignment, don't blame me if it's
>not what your teacher wanted. You'll probably need to fill it out a
>bit and check it before you use it, at minimum.
>
>Joel
  Received on Fri Aug 03 2001 - 23:07:06 CEST