Edmund Dengler wrote:
> Is the rewrite only for the literal 'X = NULL' or will it do a test
> against a value such as 'X = OLD.X' (and rewrite is OLD.X is NULL)?
It is a parse time transformation:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&frame=right&th=26ef31219ae11442&seekm=3DF52206.5060507%40mascari.com#link6
> Is there any way to match NULLS to each other (as I am looking for a
> literal row, not using NULL as the UNKNOWN). I suppose I could put in a
> dummy value for the 'Not a valid value', but it seems to be quite awkward
> when I really do want the NULL.
Normalization would have you eliminate the NULL by having another
relation whose candidate key is the same as your original table, but
those records whose attribute is NULL would simply not be present in
the child table.
Another possible solution is to define your own type with an internal
status for 'Not a valid value'...
HTH,
Mike Mascari
mascarm@mascari.com