Edmund Dengler <[EMAIL PROTECTED]> writes:
Normally, when I am comparing rows, I do want NULL <> NULL.
No, you still haven't got the point. NULL is not equal to NULL, and
it is not not-equal-to NULL either. The result of the comparison is
NULL, not true or false. This is consistent with the interpretation
of NULL as "I don't know the value". If you don't know what the value
is, you also don't know whether it is equal to some other value.
In these cases, it is recommended to either find a value which is out of range, normally, and use that in place of NULL. For examples:
-1 10^32-1 "." the_oldest_possible_date BC the_furthest_away_date AD
Another way is to put an additional column in, but I think this still has problems if you are trying to get a query to return values in a column that has NULLs and you are querying against the column that has the NULLs.
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