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Posted Tuesday, April 13, 2010 1:18 AM


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Sorry: NULL IS NULL.




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© Dr.Plch
Post #902175
Posted Tuesday, April 13, 2010 1:19 AM
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Hah, should have known Hugo would come explain everything properly - ignore my posts, concentrate on his :)


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Post #902177
Posted Tuesday, April 13, 2010 1:37 AM


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I got my point because I could guess the spirit of the question from the "UNKNOWN" option, but it's plain wrong.
NULL := NULL


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Post #902180
Posted Tuesday, April 13, 2010 2:26 AM
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Hugo Kornelis (4/13/2010)
[wrote lots of good stuff...]


Thanks for this excellent clarification which deserves an Article on its own! So you better get started!


Best Regards,
Chris Büttner
Post #902193
Posted Tuesday, April 13, 2010 2:37 AM


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Christian Buettner-167247 (4/13/2010)
Hugo Kornelis (4/13/2010)
[wrote lots of good stuff...]


Thanks for this excellent clarification which deserves an Article on its own! So you better get started!
Thanks, Chris!

I already wrote and published that article some years ago. Just not here, but on my blog. See the links in my first post.



Hugo Kornelis, SQL Server MVP
Visit my SQL Server blog: http://sqlblog.com/blogs/hugo_kornelis
Post #902198
Posted Tuesday, April 13, 2010 2:40 AM


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I opted for the NULL answer. My understanding was, and still is, that NULL doesn't mean unknown, but that any potential value is simply not there.



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Post #902199
Posted Tuesday, April 13, 2010 5:05 AM
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For me, NULL is definitely not «Unknown», since «Unknown» is a result of a logical operation.
Being in doubt i voted for NULL, but the question should have had more explanation.
Post #902283
Posted Tuesday, April 13, 2010 6:31 AM


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NULL means the absense of a value....

NULL means NULL.

NULL does not equal NULL which is very different statement from means.


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Post #902335
Posted Tuesday, April 13, 2010 6:41 AM


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And what about not mentioned option "empty value". For numerics it is clear, but for strings, it's dangerous to mix with empty string.
NULL is unassigned value - no value at all, UKNOWN is special logical value, and zero/'' are normal values.




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Post #902342
Posted Tuesday, April 13, 2010 7:08 AM
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For a question about NULL to make any sense, the context and/or the operational definition must be set.

NULL has different results in the same operations based on other settings, therefore, NULL has different definitions based on those settings.

None of that is counting certain segments of actual practice, (not theory) in which the operational definition of NULL is actually 'Treat it as you treat empty string or 0 or some other known value, because those who came before failed to set the column to be NOT NULL for one or more reasons, and we aren't allowed to change the data or the setting now'.
Post #902362
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