Re: Another view on analysis and ER
From: Jon Heggland <jon.heggland_at_ntnu.no>
Date: Thu, 06 Dec 2007 15:16:56 +0100
Message-ID: <fj909f$div$1_at_orkan.itea.ntnu.no>
>
> Yes.
>
>
> The preponderance of foreign key references will refer to the primary
> key when one designates a primary key.
Date: Thu, 06 Dec 2007 15:16:56 +0100
Message-ID: <fj909f$div$1_at_orkan.itea.ntnu.no>
Quoth Bob Badour:
> Jon Heggland wrote:
>> Minor point: Is designation of primary keys really at the logical level?
>
> Yes.
>
>> Are there any substantial logical consequences?
>
> The preponderance of foreign key references will refer to the primary
> key when one designates a primary key.
Granted, but it will be explicit which key a foreign key refers to (or it will be implicitly given by the attribute names in the foreign key). Primary key designation is neither necessary nor sufficient for this.
-- JonReceived on Thu Dec 06 2007 - 15:16:56 CET