Jon Heggland wrote:
> Bob Badour wrote:
>
>>It occurs to me a superkey reference implies something less than 3rd
>>normal form because any attributes over and above the irreducible key
>>will be functionally dependent on the foreign key.
>
> In most cases (but not all) there will be normalisation issues, yes.
> However, the foreign superkey (FSK) will typically control the
> redundancy and prevent anomalies.
>
>>Why include them in the referencing relation at all?
>
> Pragmatic reasons. For instance as an alternative to an ASSERTION-type
> join-based constraint, which many(? most? Does anybody know?) DMBSs
> don't support.
I don't follow your reasoning. If you simply omitted the dependent
attributes from the referencing relation, normal foreign key constraints
would suffice.
Received on Tue Aug 08 2006 - 07:26:40 CDT
