Re: Modelling objects with variable number of properties in an RDBMS
From: FrankHamersley <FrankHamersleyZat_at_hotmail.com>
Date: Wed, 02 Nov 2005 11:33:12 GMT
Message-ID: <Yt1af.6984$Hj2.760_at_news-server.bigpond.net.au>
>
> I know that, but what recipe does Roy suggest for, let's say, MS SQL Server
> that does not have either UDTs or other means to implement an entity with a
> higher than the table limit number of attributes, beyond offering a cute
> saying ?
Date: Wed, 02 Nov 2005 11:33:12 GMT
Message-ID: <Yt1af.6984$Hj2.760_at_news-server.bigpond.net.au>
VC wrote:
> "Jonathan Leffler" <jleffler_at_earthlink.net> wrote in message
> news:YHY9f.4683$Rl1.3852_at_newsread1.news.pas.earthlink.net...
>
>>VC wrote: >> >>>"Roy Hann" <specially_at_processed.almost.meat> wrote in message >>>news:9v-dnYE-SanY6PreRVnygg_at_pipex.net... >>> >>>>"vc" <boston103_at_hotmail.com> wrote in message >>>>news:1130765800.098046.93870_at_f14g2000cwb.googlegroups.com... >>>> >>>>>Roy Hann wrote: >>>>>.... >>>>> >>>>>>Actually no, let's not. What you have re-invented here is the tired >>>>>>old >>>>>>entity-attribute-value (EAV) design (much beloved of medical research >>>>>>wonks for some reason). >>>>> >>>>>Often they do that (EAV) not because they do not know any better but in >>>>>order to overcome a specific database physical limitations. Their >>>>>entities very often contain thousands of attributes (molecular >>>>>biology/pharmaceutical research/drug discovery) [snip]. >>>> >>>>Always check the bath water for babies... >>> >>>I beg your pardon ? >> >>There's an old saying "Don't throw the baby out with the bath water". >>In this context, it means (roughly) make sure you don't lose the benefits >>of the relational model by thowing away all the rules that help
>
> I know that, but what recipe does Roy suggest for, let's say, MS SQL Server
> that does not have either UDTs or other means to implement an entity with a
> higher than the table limit number of attributes, beyond offering a cute
> saying ?
Was MS SQL selected before the requirements were expressed (1 black mark) or after (10 black marks)?
Cheers, Frank. Received on Wed Nov 02 2005 - 12:33:12 CET