Re: FOREIGN KEY: MATCH FULL

On Wed, 5 Sep 2001, Gabriel Fernandez wrote:

> Hi,
>
> What does it mean the MATCH FULL parameter in a foreign key specfication
> ?
>
> It seems it is only valid for a multi-column foreign key: What's a
> multi-column foreign key ?

It's only different on multi-column fks, it's valid but uninteresting
on singles.  A multi column foreign key is something like the one
in the following:
create table foo (
 a int,
 b int,
 foreign key (a,b) references bar
);
The key that's being checked is the combination of a and b.

For the unspecified match type, if either is NULL, the constraint
is passed.  For MATCH FULL, either both must be non-NULL and match
in the other table or both must be null for the constraint to pass.