Re: Proposal: 6NF

From: David Cressey <>
Date: Fri, 13 Oct 2006 04:17:48 GMT
Message-ID: <MrEXg.5488$WD1.3719_at_trndny04>

"Hugo Kornelis" wrote:

>sloppiness in the hands of the unwashed!
> If there was any chance to get this changed, I'd favor a mandatory
> inclusion of explicit NULL or NOT NULL for every column.

If I could go back in time and get it right to begin with, here's what I'd favor:

Get rid of NOT NULL as a column property. Add a new key word, OPTIONAL that, as part of a column definition, permits omission of the value, a la NULL. By default, all columns have a NOT NULL constraint unless overridden with the OPTIONAL property.

Get rid of the Boolean value UNKNOWN.
Evaluate booleans that can be evaluated to either TRUE or FALSE. If a Boolean expression cannot be evaluated, don't return any value at all. If there's no trapping mechanism, then return NULL, indicating that the expression has no value.

It's probably to late for this kind of surgery on SQL. Received on Fri Oct 13 2006 - 06:17:48 CEST

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