Re: Question on Primary Keys

If the existence of the user is depending on the existence of an organisation unit you should make it a mandatory FOREIGN key, not a primary key. Primary keys are intended to identify the uniqueness of a record in its own table, foreign keys are intended to represent relationships between different entities.

Reinier.

Jan Lenders <J.Lenders_at_Betuwe.net> wrote in message news:8se93i$qm3$1_at_nnrp1.deja.com...
>
> > Each USER belongs to an ORG_UNIT.
> > (a) The USER table can have a combined PK of USER_ID & ORG_UNIT_ID
> > (b) The USER table can have a PK of USER_ID (some sort of unique
> > number) and have ORG_UNIT_ID as a FK.
> >
> Raju,
> If the existence of a USER object is dependent on the existence of a
> ORG_UNIT you should make the ORG_UNIT_ID (foreign key) a primary key in
> the USER table.
>
>
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> Before you buy.
Received on Mon Oct 16 2000 - 03:24:06 CDT