> Kind of handy
>
> Like extra pizza topping: Null, 'Bacon', 'Cheese'
>
> Null = No extra topping. Subsequently taking advantage
> of the 'no exist' behavour of the Null value.

Given IBs handling of NULLs (all arguments about "correctness" aside),
I think you are best advised to either...

* Setup triggers to catch nulls and convert to empty strings
or
* Setup a specific entry for "No Topping" (perhaps prefixed with a
space or special character to sort to the top or bottom of the list
for convenience).

I think I know what you mean about the 'no exist' behaviour but I have
always found this to be entirely confusing and lacks explicit
expression of your intensions. I prefer: WHERE TOPPING<>'NO TOPPING'
rather than letting SQL blindly apply its NULL column rules.


Geoff Worboys
Telesis Computing