Re: Proposal: 6NF

On Fri, 13 Oct 2006 04:17:48 GMT, David Cressey wrote:

>
>"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.

Hi David,

Would NULL as a result from a boolean expression differ only in name from the current UNKNOWN, or would it actually behave differently? For example, what would the result be of the boolean expression:

   (1 > 2) AND (3 = NULL) AND (4 < 5)
or, shorter,

   TRUE AND NULL AND FALSE
>It's probably to late for this kind of surgery on SQL.

Aye. But we can dream...

Best, Hugo Received on Fri Oct 13 2006 - 23:39:00 CEST