Thanks Jim. Not only do NULLs group together, but they are considered "not distinct" when performing set-based operations like UNION, EXCEPT, INTERSECT, and when retrieving DISTINCT rows: http://www.sqlservercentral.com/articles/Advanced+Querying/2829/%5B/url%5D.

kaspencer (4/3/2008)

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That is a good question.

Personally, when I design database schemas where some of the data has to be date-ranged (and lots of data items in most data models...

dbishop (4/3/2008)

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So, when you boil all this down, how do you handle things like DateTerminated, DisconnectDate (specifically DATETIME datatypes) when the event has not occurred. You know that an employee...

Very Zen-like philosophy Steve 🙂

Ian Crandell (4/1/2008)

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This is also my first time reading this and I completely concur. This makes NULLs much clearer.

I have one question about the truth table (and this might...

Jeff Moden (3/28/2008)

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Mike C (3/28/2008)

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I get a clustered index scan when I run your code. The optimizer expands it out to RowNum <> 1 AND RowNum <> 2 AND RowNum...

Lars Huttar (3/28/2008)

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Mike C (3/28/2008)

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Would I be willing to concede that the statement "NULL is not equal to any other value, or other NULLs" is incorrect? Absolutely if the...

Jim Russell (3/28/2008)

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Having just gone through 11 (enlightening) pages of this thread, I hope I just have not missed the answer to my question:

Since nulls will group together in a...

Jeff Moden (3/28/2008)

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??? :blink: Maybe I'm reading this wrong, but WHERE NOT IN most...

Gregg Walker (3/28/2008)

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Very nice article Michael on a topic where the details really count.

I had never heard of the COALESCE function before. We use Informix as our primary database...

Bill Wimsatt (3/28/2008)

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Just another point of view. I live in an Oracle, DB2, SQL Server world. Here is a companion article on Oracle's forums which came out about the same...

Lars Huttar (3/28/2008)

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Matt Miller (3/28/2008)

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Lars - the issue you seem to be hammering on stems from treating NULL as if it were a value. NULL is technically not a...

Would I be willing to concede that the statement "NULL is not equal to any other value, or other NULLs" is incorrect? Absolutely if the opposite can be demonstrated:...

Lars Huttar (3/28/2008)

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Thanks for a very informative and thought-provoking article. Shows me I still have lots to learn about SQL.

I have a point of unclarity or inaccuracy to pound on...

Matt Miller (3/28/2008)

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Mike C (3/28/2008)

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I'd agree that this is probably a common usage, and as long as you're comfortable with using NULL to represent multiple states that might be adequate....