Re: One-To-One Relationships

From: Bob Badour <>
Date: Sun, 02 Dec 2007 11:10:07 -0400
Message-ID: <4752cad3$0$5277$>

Jan Hidders wrote:

> On 1 dec, 15:03, JOG <> wrote:

>>[...] let me give an example as to why I find
>>the breakdown into entities and relationships deleterious. Say I have
>>two entity types staff_members and subjects, and a relationship
>>staff_member -- teaches --> subject
>>This is all good and fine until a requirement changes that we need to
>>record the day the lecture is given on.

> Yes. Relationships may become Entities, Roles may become
> Relationships, Attributes may becomes Relationships, etc. As David
> remarked, there are ER dialects like ORM that smoothen this a bit, but
> you can never make that really go away. These problems have
> counterparts in the RM where foreign keys may become tables by
> themselves, or tables are split because a one-to-one relationship has
> become a one-to-many one.

ORM = ER ?!? Since when? Received on Sun Dec 02 2007 - 16:10:07 CET

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