Re: Foreign key problem

Je Mon, 25 Jun 2001 09:34:01 +0200 (CEST),
Andreas Tille <tillea(at)rki(dot)de> scribis:

> CREATE TABLE ResKulturDetail
> (
> IdLabNr int,
> IdIndex smallint
> );
>
> CREATE TABLE ResKulturDetailDay
> (
> IdLabNr int,
> IdIndex smallint
> );
>
> CREATE INDEX IX_IdLabNr_KulturDetail ON ResKulturDetail(IdLabNr) ;
>
> ALTER TABLE ResKulturDetailDay ADD CONSTRAINT FK_ResKulturDetailDay
> FOREIGN KEY (IdLabNr,IdIndex)
> REFERENCES ResKulturDetail (IdLabNr,IdIndex) ;

> Can anybody explain, why the foreign key constraint fails?

According to the documentation for CREATE TABLE:

In addition, the referenced columns are supposed to be the columns
of a UNIQUE constraint in the referenced table, however Postgres
does not enforce this.

Well, it looks like PostgreSQL *does* enforce it. Try it with:

CREATE UNIQUE INDEX IX_IdLabNr_KulturDetail
ON ResKulturDetail(IdLabNr, IdIndex) ;

I'm not sure why this restriction is necessary...

--
Itai Zukerman <http://www.math-hat.com/~zukerman/>