Re: Modeling Data for XML instead of SQL-DBMS
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 28 Oct 2006 00:04:49 +0200
Message-ID: <454281d2$0$326$e4fe514c_at_news.xs4all.nl>
>
> I'll just take this point for now and see if I can understand what you
> are saying.
>
> What I am trying to make clear is that we can use tools where we can
> indicate a Books and an Authors entity, without adding a third relation
> into the mix. We might have a Books relation that includes an
> attribute whose value is a list (or set) of Authors and an Authors
> relation with an attribute that is a list of Books. If there are no
> attributes in the relationship between book and author that are
> relevant to our system, there is no need to introduce any relationship
> entity.
Date: Sat, 28 Oct 2006 00:04:49 +0200
Message-ID: <454281d2$0$326$e4fe514c_at_news.xs4all.nl>
dawn wrote:
> mAsterdam wrote:
>> dawn wrote:
<snip>
>>> Why should they be forbidden when they are quite viable logically and >>> can be implemented in some DBMS tools? >> [m:n] >> No 'should', really. Whatever the implementation will be, >> at some point in the process the many to many relationships >> will have to be transformed into named things >> (SQL: tables with at least two foreign keys, Codasyl: records >> in at least two sets, etcetera).
>
> I'll just take this point for now and see if I can understand what you
> are saying.
>
> What I am trying to make clear is that we can use tools where we can
> indicate a Books and an Authors entity, without adding a third relation
> into the mix. We might have a Books relation that includes an
> attribute whose value is a list (or set) of Authors and an Authors
> relation with an attribute that is a list of Books. If there are no
> attributes in the relationship between book and author that are
> relevant to our system, there is no need to introduce any relationship
> entity.
I did not know that products with anonymous m:n relationships exist.
> Am I missing the mark on what you are saying?
No, I think you get it.
This makes the requirement for having to get rid of
m:n relations an implementation dependent one.
Received on Sat Oct 28 2006 - 00:04:49 CEST