Re: Document NULL

On Fri, May 3, 2024 at 2:47 PM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Thu, 2024-05-02 at 08:23 -0700, David G. Johnston wrote:
> > Version 2 attached.  Still a draft, focused on topic picking and overall structure.
>
> I'm fine with most of the material (ignoring ellipses and typos), except this:
>
> +    The NOT NULL column constraint is largely syntax sugar for the corresponding
> +    column IS NOT NULL check constraint, though there are metadata differences
> +    described in create table.
>

the system does not translate (check constraint column IS NOT NULL)
to NOT NULL constraint,
at least in domain.

for example:
create domain connotnull integer;
alter domain connotnull add not null;
\dD connotnull

drop domain connotnull cascade;
create domain connotnull integer;
alter domain connotnull add check (value is not null);
\dD