Re: [HACKERS] Re: NULL & NOT NULL

> "Thomas G. Lockhart" <lockhart@alumni.caltech.edu> writes:
> >>>>>> create table authors (
> >>>>>> zip             char(5)         null
> >>>>>> );
> 
> > Sheesh. After that long song and dance about why we can't implement
> > this, it turns out that it works fine. We had been trying to implement a
> > slightly different syntax, "WITH NULL", which conflicted with the
> > SQL92-defined data type declaration "TIMESTAMP WITH TIME ZONE".
> 
> > The "Practical SQL Handbook"-compatible form will be available in the
> > next full release of Postgres. Thanks.
> 
> Now that we have the syntax problem straightened out: I'm still confused
> about the semantics.  Does a "NULL" constraint say that the field
> *must* be null, or only that it *can* be null (in which case NULL is
> just a noise word, since that's the default condition)?  I had assumed
> the former, but Bruce seemed to think the latter...


Can be null.  Noise word.  At least that is what I rememeber Thomas
saying, and because it was noise, we removed it.  In fact, it doesn't
look like the standard accepts it, but there is no reason we can't.

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