> I have written a billing application where you can assign discounts
> for the customer: 5%, 7%, ...
> or even <none>.
>
> When the application creates the invoice, the assigned discount is
> chosen from the lookup table. If the lookup field for the customer is
> NULL, no discount is computed.

In this case I would expect to be putting a number in the
discount field - even if it is filled in from a lookup
table. The DEFAULT would be 0. Then I can use that field in
COMPUTED fields, where NULL would not include the reset of
the sum. Even my VARCHAR fields get defaulted to a blabk
line now, so that I don't have any supprises when I
concxatonate. NULL is not an appropriate 'value' for many
fields.

--
Lester Caine
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L.S.Caine Electronic Services