Re: One to One relationships

How about considering this from the access/security aspect? Perhaps there is information that you want restricted to/from a particular set of users... that 'sensitive' info could be moved to a separate table and protected as necessary.
John A. Mason

"stu" <smcgouga_at_nospam.co.uk> wrote in message news:b88rd8$9oo$1$8300dec7_at_news.demon.co.uk...
> If an entity must have exactly one thing what is the point in making
another
> entity (table) for the 'thing'?
>
> Eg: One person must have one and only one house. A person will stay in
> that house forever! (my attempt at making up a 1:1 relationship) Maybe
> this is my problem: It is difficult to find a model that has a 1:1?
>
> What do we gain from separating people and houses? Why would we not want
to
> store house as an attribute of person or vice versa?
>
> Guess what im asking is when should house become a separate entity vs an
> attribute?
>
> Practically speaking performing large row joins like this can be expensive
> and if we have a compound primary key we do not need 2 tables. Are there
> any other things I should consider?
>
> Im talking generically here. Im not actually interested in people and
> houses. If you have a better eg please use that.
>
> Cheers
> Stu
>
>
Received on Wed Apr 30 2003 - 01:31:26 CEST