Re: postgresql vs mysql

On Thu, 22 Feb 2007, Erick Papadakis wrote:

> Why should a NULL be different from an empty string, what's the big
> mysterious difference?

   Long ago and far away, when I was in the Army, we had quite a few soldiers
whose name took the form 'John NMI Doe.' That's because the Army -- even
before computers were ubiquitous -- needed something in the forms for middle
initials. If you did not have a middle name or initial, one was assigned to
you: NMI (No Middle Initial). This did not mean that the middle initial was
unknown (NULL), but that it did not exist (blank).

   If you have a credit card, would you prefer the balance to be blank or
unknown? How would the bank select all those with no balance rather than
those for whom a balance is unknown?

   I'm sure you can think of dozens of more situations like these.

Rich

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