Andreas Joseph Krogh wrote:
> This has been been discussed before, but Oracle behaves differently, and IMHO
> in a more correct way.
>
> The following query returns NULL in PG:
> SELECT NULL || 'fisk';
>
> But in Oracle, it returns 'fisk':
> SELECT NULL || 'fisk' FROM DUAL;
>
> The latter seems more logical...
>
>
When in doubt, consult the standard ... Oracle's treatment of NULL is
known to violate the standard, IIRC. Your measure of correctness seems
to be "appears to me more logical", but ours is "complies with the
standard".
In any case, why should null have a string value of '' any more than it
should have a value of 'blurfl'?
Your analogy elsewhere with aggregate functions like sum() is not
relevant, as these are documented to ignore null values.
cheers
andrew