----- Original Message -----
From: "Martijn Tonies" <m.tonies@...>
To: <ib-support@yahoogroups.com>
Sent: Friday, March 07, 2003 1:55 PM
Subject: Re: [ib-support] Re: Database corruption after alter table


> Hi Alexander, Carsten,
>
> > > But why can i insert a foreign key for this column without any
> > > exception.
> > > The field id_mitarbeiter is primary key for t_mitarbeiter and there
> > is
> > > no null value allowed.
> >
> > Carsten, I can't recall exactly when (what was FB build number, but
> > definetely before release of FB1) this feature was included, but FK
> > can contain not only values which match PK of referenced table but
> > nulls too. Perhaps Martijn can remember more exactly, he was among
> > those who wanted this feature. Personally I prefer old, more
> > restrictive behaviour, but I was among minority and feature was
> > approved by developers and implemented.
>
> Actually, I think I've wanted a feature related to UNIQUE constraints
> with NULLs ... And I don't think it was included in Fb1. As for the FK,
> as far as I know, they will still only allow values as to be found in the
> constraint (unique/pk) they are referring to.
>
>
No, it seems that null values are allowed.
(i don't see the null values with ibexpert, but Alexander has shown that they are null)
The main problem is that this leads to an unrestorable database.

gruß
Carsten