Re: constraint -- one or the other column not null - Mailing list pgsql-general

On Wed, Sep 06, 2006 at 12:04:18AM -0700, George Pavlov wrote:
> I have two columns, both individually nullable, but a row needs to have
> a value in one or the other. What is the best way to implement the
> constraints?

check (a is null != b is null);