Re: multi column foreign key for implicitly unique columns

В Втр, 17.08.2004, в 16:46, Tom Lane пишет:

> I think one reason for this is that otherwise it's not clear which
> unique constraint the FK constraint depends on.  Consider
>
>     create table a (f1 int unique, f2 int unique);
>
>     create table b (f1 int, f2 int,
>             foreign key (f1,f2) references a(f1,f2));
>
> How would you decide which constraint to make the FK depend on?

Either way, the semantics are the same, right?

--
Markus Bertheau <twanger@bluetwanger.de>