Subject Re: clearing comboBox in grid does not produce NULL
Author scronkey
Hi Marco,
thanks for your reply.

Just checking something with your description below:

(assuming A is old.VAL & B is new.VAL)

What if A was NULL & B was not?
This would not then evaluate to true, as A=B won't work, as one of
the values is NULL,
and ((A is null) and (B is null)) would not evaluate as one of the
values is not NULL.

Am I correct here?

Is the solution to also include checks like:

I find it a little cumbersome to have to evaluate so many
conditions, when it seems logical to me that even though NULL is a
state, not a value, clearly '7' and NULL are not equal...


> Until then (and I don't know if it will be introduced, since some
> "purist" does not want it, but this is another story) you must use
> something like this to catch field OLD/NEW changes:
> not ( A = B or ((A is null) and (B is null)) )
> and beware this situation too:
> ( A = B ) <==> not ( A <> B )
> doesn't hold as soon as nulls are involved!
> regards
> Marco Menardi