Re: Is this bad design ?

From: ben brugman <ben_at_niethier.nl>
Date: Thu, 11 Mar 2004 13:26:26 +0100
Message-ID: <40505af3$0$6572$4d4ebb8e@read.news.nl.uu.net>

"Fabian Buettner" <green_at_tzi.de> wrote in message news:405055BA.2020608_at_tzi.de...
> > Suggestion A:
> > Splitting the table in two were one table only holds the
> > valid mothers and one table holds the non-valid mothers.
>
> No. One table (Mothers) contains all mothers (valid and invalid) with
> all their attributes. The other table (ValidMothers) contains only the
> mother_ids of valid mothers. Thus ValidMothers models a *subset* of
> Mothers. Then, if you want a reference to only valid mothers, you can
> reference ValidMothers.mother_id instead of Mothers.mother_id.

Thanks, did my reading to quickly, sorry for that.

This looks like a good solution.
(Could be implemented in 'triggers' so that the application does not have to notice, if the 'valid field' is kept in the mother).

ben

>
> Fabian
>
Received on Thu Mar 11 2004 - 06:26:26 CST