--- Svein Erling <svein.erling.tysvaer@...> wrote:

> Of course you get NULL, NULL is a state meaning UNKNOWN - something
> that can be very different from an empty string. Hence, you can never
>
> know the result when NULL is involved in any computation and the
> result must be NULL.

That's correct; according to "SQL Instant Reference" by Martin Gruber,
"If either of the strings being concatenated is NULL, the result of the
concatenation also is NULL." (p. 248.)

Interestingly, though, I just tried it with Oracle 8i and it treated a
null field as a zero-length string.


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