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Re: Relation problem

From: Jan Hidders <hidders_at_REMOVE.THIS.win.tue.nl>
Date: 22 Jan 2001 15:30:53 GMT
Message-ID: <94hjnd$on7$1@news.tue.nl>

Kristian Damm Jensen wrote:
> Jan Hidders wrote:
> >
> > Of course, but it also means that you will still have two tables Indiv.
> > and Organ. that contain the class specific attributes and a foreign key
> > to the Parties table. And the reverse of this foreign key is a "split
> > foreign key".
>
> Correct. That is inherent in the nature of the data and can not be
> avoided.

Exactly my point. :-)

> What can be avoided is some of the performance problems. Without the
> supertype referential integrity from Adresses to Individuals and
> Organizations can not be maintained using an index. With Parties it can.
>
> Ah, you say, but then you will just move the problem on to maintaing
> referential integrity between Parties and Individuals/Organizations. But
> as this will not be updated (!) the is reduced to deletion and
> insertion, which I believe will happen much more infrequently.

Very good point and you might be right about the number of updates. But it may depend upon the type of organizaton that you are dealing with. In some organizations clients come and go, in others they stick with the same supplier for years.

-- 
  Jan Hidders
Received on Mon Jan 22 2001 - 09:30:53 CST

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