Re: One-To-One Relationships

From: Bob Badour <>
Date: Sun, 02 Dec 2007 11:50:06 -0400
Message-ID: <4752d432$0$5266$>

Jan Hidders wrote:

> On 2 dec, 16:10, Bob Badour <> wrote:

>>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?
> Since the objects and the fact-types in ORM are basically the same
> thing as entities and relationships in ER.

Basically the same? Or the same? Received on Sun Dec 02 2007 - 16:50:06 CET

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