Ouch, yes that is a bit of a glaring error. I've seen...

Craig Farrell (10/13/2010)

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I work in MS SQL Server and T-SQL. Because of that, and because an index can give me performance where a constraint will not, but still takes...

Craig Farrell (10/13/2010)

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In SQL Server a unique index on non-nullable columns is just a key by another name. Unique indexes and uniqueness constraints are simply two different ways to create...

I doubt that a password would be a key. Most systems that I know of don't require passwords to be unique.

In SQL Server a unique index on non-nullable columns is...

Tom, I agree with everything you wrote except your suggestion that keys should be stable:

Stability is usually a desirable...

I think you are confusing two very different things: the NULL marker needed to indicate an absent datum and the extra truth value needed for 3VL. It's probably because you...

Tom.Thomson (8/11/2010)

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as indicated by the the silly example I provided in a previous comment, where (1) you either define 10**34 tables before you start inserting data, or accept a situation...

PaulB-TheOneAndOnly (8/9/2010)

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In my opinion Zeros and Nulls are not the same and do not represent the same thing.

Lets go back to the blood pressure example.

Picture an ER where an automated...

Matt Miller (#4) (8/8/2010)

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Again you are getting yourself into trouble by bringing up the physical reality. Tell me - what EXACTLY is the physical reality of an empty set?

And...

The count of members in a set is not the same as memberwise addition. Taking two 2 balls from a set with two balls in it results in a...

As to addition and multiplication being a unary operation, I'd be REALLY interested in a mathematical reference actually pointing that out (my 2nd grade math teacher would like a copy...

PaulB-TheOneAndOnly (8/8/2010)

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So... at reservation time... which value do you use to populate date_pickup_actual and date_return_actual considering business specs are stating that those values are "not known" at that time? ......

That's true. The empty set is sometimes called the null set. However, the null set (=empty...

[Sorry for the delayed follow up]

Tom.Thomson (8/1/2010)

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I'm appalled. You want to stick some values in there although the database does not have any values, and you think that doing...

Matt Miller (#4) (8/1/2010)

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We seem to be circling around semantics again. In my book I use unknown to mean "I know nothing of this, to include whether it should...