Re: So what's null then if it's not nothing?

From: vc <>
Date: 25 Nov 2005 06:03:57 -0800
Message-ID: <>

Jon Heggland wrote:
> You say the empty string is the same as "no value at all", and say we
> should call this concept of "no value at all" NULL for other data types.
> Now, the empty string is a perfectly normal string. You can do string
> operations on it: concatenate it, find its substring, find its length
> and so on. For an integer variable that is NULL, it is very different.
> You cannot do integer operations on it; you cannot add it to another
> integer, or multiply it, for example.

You are quite right.

This empty string discussion is a bit strange to put it mildly. If one remebers what a string is (a list of characters), then an empty string is just an empty list, a perfectly legitimate value that one can use in a very much the same fashion as the integer zero.

The SQL'92 standard clearly differentiates between an empty string and NULL as do the majority of commercial RDMSs with Oracle being a notable exception. Received on Fri Nov 25 2005 - 15:03:57 CET

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