Re: null foreign key column

On Tue, Feb 11, 2003 at 16:55:28 +1300, Arunachalam Jaisankar <jsankar@xtra.co.nz> wrote:
> Hi all,
> 
> I would like to have a foreign key column in my table which allows null value also.
> But the below create table sql command doesn't accept null value for person_id.
> How to do in postgres?
> 
> create table event
> (
>     event_id               serial                not null,
>     event_description      char(255)                     ,
>     person_id              serial                        ,
>     primary key (event_id),
>     foreign key  (person_id)
>        references person (person_id)
> );

I don't think you want to use serial type for a value that references
another table. Use integer instead. Serial also implies not null which
is why you couldn't stick null values into that field.