Re: 3vl 2vl and NULL
On 4 Dec 2005 17:57:01 -0800, michael@xxxxxxxxxx wrote:
(snip)
>OK. There is one fundamental problem with this. Some of those NULLs in
>those tuples might represent that we know something is empty - so it
>has to be treated as a known value. All NULLs are not created equal.
<sigh>
Hi Mike,
No. If something is known to be empty, it's not stored as NULL. At least
not in SQL databases (which this thread is about, IIRC).
If a comment is empty, iut's stored as the empty string (''). If a
container is empty, it's contents is stored as zero gallons (0). Dates
can't be empty. (Days can be, though - that's stored as an absence of
rows in the Events table).
Best, Hugo
--
(Remove _NO_ and _SPAM_ to get my e-mail address)
.
Relevant Pages
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(comp.databases.theory) - P.S.
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(microsoft.public.sqlserver.programming) - Re: All hail Neo!
... That said perhaps the fact that nulls do exist in the RM today taken with your confirmed view that they shouldn't is implied confirmation of my rather unlikely original thought...he says stepping back two full paces - did I write that? ... is the set containing an empty set and is the canonical form of all sets with cardinality 1. ... and 1 figure by tying into the formalism for whole numbers as shown above. ... I can state that I don't hold that nulls cause _great_ damage (although neither does Semtex in capable hands for a proper purpose) and I certainly believe that they do serve a purpose. ...
(comp.databases.theory) - Re: All hail Neo!
... From there I expect anything brought to this issue by theory will be elegant, ... Bags and nulls are quite apparently not but from where I am now the null at least seems the lesser of evils viz my post in the "beautiful mind" thread. ... is the set containing an empty set and is the canonical form of all sets with cardinality 1. ... I can state that I don't hold that nulls cause _great_ damage and I certainly believe that they do serve a purpose. ...
(comp.databases.theory) - Re: Alter table by adding new column with not null
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