Re: Normalization and DBMS

From: Leandro Guimarães Faria Corsetti Dutra <leandro_at_dutra.fastmail.fm>
Date: Wed, 12 May 2004 00:46:00 -0300
Message-ID: <pan.2004.05.12.03.46.00.535494@dutra.fastmail.fm>

Em Tue, 11 May 2004 22:40:10 -0500, Dawn M. Wolthuis escreveu:

> "Leandro GuimarÃ£es Faria Corsetti Dutra" <leandro_at_dutra.fastmail.fm>
> wrote in message news:pan.2004.05.12.03.22.43.667655_at_dutra.fastmail.fm...

>> Em Tue, 11 May 2004 20:10:10 -0500, Dawn M. Wolthuis escreveu:
>>
>> > it seems to have a direct correlation to the flexibility of a system
>> > to withstand years of requirements changes
>>
>> Quite to the contrary.  With nested tables, the only way to ever reach
>> the subtable is thru the supertable.

>
> What problems are caused by this? I suspect there are some, but then
> there are tradeoffs.

See how you want to have it both ways. You want to 'withstand [...] requirement changes', but also a less powerful, more complex, less flexible structure.

> One thing that works well is the integrity -- when
> the parent goes away, so does the child table and there is no chance that
> a child will be born without a parent.

This is trivial. Even SQL does it right.

-- 
Leandro GuimarÃ£es Faria Corsetti Dutra           +55 (11) 5685 2219
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Received on Tue May 11 2004 - 22:46:00 CDT