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Re: foreign vs primary key

From: Leandro Guimar„es Faria Corsetti Dutra <leandrod_at_mac.com>
Date: Thu, 20 Sep 2001 00:18:06 -0300
Message-ID: <3BA95FEE.8050102@mac.com>


mikeg wrote:

>
> Thanks, I can see that but what is the significance? Why is it necessary to
> identify the foreign key? How are they used? Aren't primary keys enough?

        You really, really, really should read at least Chris J Date's An Introduction to Database Systems.

        Or in other words, RTFM.

        But the idea is to enforce the integrity of the database, more specifically referential integrity, not allowing a child without a parent.

        In fact even FKs are not enough. A proper, complete relational system (*not* SQL!) would in fact do for a complete rules system.

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Received on Wed Sep 19 2001 - 22:18:06 CDT

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