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Re: Oracle NULL vs '' revisited

From: Thomas Kellerer <>
Date: Fri, 17 Aug 2007 19:47:55 +0200
Message-ID: <>

Serge Rielau wrote on 17.08.2007 19:38:

>> I would be interested: if this is important for character columns, 
>> then I assume this is important for other columns as well.
>> How do you implement that distinction for e.g. NUMBER or DATE columns?

> If I get an assignment and I hand in an empty sheet that would be well
> empty. I typed zero characters.
> If I don't hand it in it is missing. It is not decidable whether my work
> is good or bad, long short.. there is the NULL.
If I don't hand it in, I don't "create a row in the database" that is something different compared to handing in an empty "row/assignment"

> For numbers I think one can reasonably argue that 0 is the equivalent of
> empty.

Hmm. I get an an assignment where I should calculate something. I hand in a sheet where I put 0 (zero) as the solution. So that is the same as handing in an assignment where I didn't enter anything. Doesn't sound logical to me.

> I don't think that there is a similar "empty" concept for dates.
That's my point. Character seems to be the only data were everybody requires the distinction between "nothing" and "empty" but nobody has ever requested this distinction for dates or numbers.

> Question: If empty strings make no sense for VARCHAR, why have them for
> CLOBs? AFAIK Oracle has helper functions to produce empty lobs.
I think that is a mere technical reason as for the CLOB some "management structures" (such as a locator) need to be created while this is not necessary with character data.

Thomas Received on Fri Aug 17 2007 - 12:47:55 CDT

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