designing inheriting entities

29 Nov 2007 9:50 AM

Emre DÝNÇER

Dear All,
our customer has 3 kinds of entites
the first one is the ApplicationCenter where students can register to
exams...
and there are types of app centers like University offices, high schools
etc.. these types goes to another table..
and finally each type has its own instances like University one ,
university2 , univ3 etc. which means there are several more tables Like
universities , highschools , examCenters etc...

the requirement is to have ADD/Edit/Delete screens of all ApplicationCenters
of the customer..
the listing of the centers and their info is straightforward however when it
is time to edit many entities needs to be updated at the same time
...........

i am trying to figure out a table design where i can build sort of
inheriting entities..
any clue?
best regards..
emre dincer

29 Nov 2007 1:16 PM

David Portas

Emre DÝNÇER wrote:

Show quote

> Dear All,
> our customer has 3 kinds of entites
> the first one is the ApplicationCenter where students can register to
> exams...
> and there are types of app centers like University offices, high schools
> etc.. these types goes to another table..
> and finally each type has its own instances like University one ,
> university2 , univ3 etc. which means there are several more tables Like
> universities , highschools , examCenters etc...
>
> the requirement is to have ADD/Edit/Delete screens of all ApplicationCenters
> of the customer..
> the listing of the centers and their info is straightforward however when it
> is time to edit many entities needs to be updated at the same time
> ..........
>
> i am trying to figure out a table design where i can build sort of
> inheriting entities..
> any clue?
> best regards..
> emre dincer

It is possible to ensure that each common attribute appears only in
one place in the hierarchy for each type of entity. Therefore the
problem of updating the same attribute in multiple places won't arise.

Fifth Normal Form and the Principle of Orthogonal Design are two
principles that will help you achieve a good model. Google for them if
you aren't already familiar with them.

--
David Portas