Re: if !NULL ?

On Thu, 16 May 2002, Lev Lvovsky wrote:

>
> ok, so more odd-ball questions
>
> I have two columns in a table:
>
> bool_bill | billing_id
>
> one is a boolean that determines if we bill a customer, and the other one
> is NULL if we don't, and has a billing_id of that customer if we do. the
> billing_id uses a foreign key on the billing table to check that the
> billing_id exists.
>
> what I'd like to do is if bool_bill = y, then there has to be something in
> billing_id (automatically checked with the foreign key).
>
> again, do I need a function for this?

I think a table check constraint like:
(bool_bill=false or billing_id is not null)
will make billing_id not accept nulls when bool_bill is true.