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Re: So what's null then if it's not nothing?

From: Jon Heggland <heggland_at_idi.ntnu.no>
Date: Thu, 24 Nov 2005 08:42:25 +0100
Message-ID: <MPG.1def8d4d22794afd989708@news.ntnu.no>


In article <fjl9o1tj8b3d5ehiso74d9jo3m809enoe3_at_4ax.com>, hugo_at_pe_NO_rFact.in_SPAM_fo says...
> >You mean you would create a table for each *combination* of attributes?
> >What on earth for?
>
> Hi Jon,
>
> I wouldn't. It's a suggestion that has been made in this thread as a way
> to model the data without the need for NULLs. I merely pointed out the
> weak spot in this method.

Julian M wrote

"2- You create a parent/root entity/table and make a subtype for each optional field"

To interpret this as leading to an exponential (as opposed to linear) number of tables smelled of a straw man to me. Though I must admit I don't really see the difference from Julian M's

"1 - Put the optional field in another table, with a 1:1 relationship (this is usually mentioned in normalisation books/courses)"

---so maybe it was I who misread it. Never mind.

-- 
Jon
Received on Thu Nov 24 2005 - 01:42:25 CST

Original text of this message

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