Nadrek (8/20/2010)

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Simple example:

DISK ROTATIONAL SPEED

A 15000

B ...

Matt Miller (#4) (8/18/2010)

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True except that in practice, actually being able to make that distinction is an awfully big step.What do you do WHILE you actually decipher whether the machine...

That's something I agree with 100% - let's avoid using nullable columns when it is practical...

Little boxes

edit: I see I was behind on this one. Nevertheless, We shall overcome.

Various parts of mathematics use a NULL-like concept. The ones which to me seem to be the closest to the NULL of relational databases crop up in Chris Strachey...

mtillman-921105 (8/16/2010)

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I was a philosophy major (and a psychology major by the way), so I started reading my book on elemetary logic about empty sets over the weekend. Now here...

Jeff Moden (8/13/2010)

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mtillman-921105 (8/12/2010)

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Not that I'm trying to put an end to this logic discussion, I'm not: but look. Can't we accept that in certain cases NULLs are useful...

Holland is two provinces...

David Portas (8/12/2010)

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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...

David Portas (8/11/2010)

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Why is the Scottish legal system an example of 3VL or missing information? I don't think it's anything of the kind. It's a question with three very specific...

LutzM (8/11/2010)

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Steve,

you asked for some improvement ideas for the SSC site: add the option to upload (and play) sound files :-D:-D

Then we could actually hear the pronounciation of all...

jcrawf02 (8/10/2010)

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As more of an end user than a theorist or dba, I'll chime in on that one. The absence of data is not equivalent to zero, it means the...

PaulB-TheOneAndOnly (8/10/2010)

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I know you proposed to create an actual-pickup-date and an actual-return-date tables to hold that information but that would end with tables having a 1-to-1 relationship with Reservations table...

Jeff Moden (8/9/2010)

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mtillman-921105 (8/9/2010)

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Actually, this breaks a cardinal rule in database design - we are using one column for more than one kind of data. It answers two questions: Was...

David Portas (8/8/2010)

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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...