Re: NULL versus empty string

Hi Tim,

Tim schrieb:
> I would guess that the logic is that if you don't want to allow null,
> then you want an actual value and "" while not being null, is not really
> a value conceptually. I mean, if "" was acceptable, why not just allow
> null?

NULL means: 	I have no value
"" means:	I have the value ""

The difference is more obvious using a number datatype:
NULL means:	I have no value (as before)
0 means:        I have the value 0

For me, there is a big difference between NULL and a value valid for the column. If you do for example
SELECT SUM(<col>) FROM <table>
you will get the value NULL if your column cotains NULL values but you will get a numeric result when you have 0 stored instead of NULL. In this case, calulations depending on this result could be false (e.g. average).

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Mit freundlichen Grüßen / Best Regards
Michael Gast
SEPP MED GmbH