Yes, thanks Andy, but if you have a primary key, do you NEED that other
table?   Or are you not referring to the key table?


Sorry, but am I being dense?


Cheers,
Mike Kear
Windsor, NSW, Australia
AFP WebWorks


-----Original Message-----
From: Andy Ewings [mailto:[EMAIL PROTECTED]]
Sent: Saturday, 28 September 2002 2:01 AM
To: SQL
Subject: RE: Why External keys?

You do this so that referential integrity is enforced by the database i.e.
you don't end up with recs in one table with no corresponding rec in
another.

-----Original Message-----
From: Michael Kear [mailto:[EMAIL PROTECTED]]
Sent: 27 September 2002 16:54
To: SQL
Subject: Why External keys?


Sorry if this is such a basic question as to be stupid,  but why do you
sometimes have foreign keys?   I've looked at  MS's Books Online, but that
only tells me how to do it, not why I'd want to,  which is typical of
Microsoft's documentation.


On my tables in MS SQL2000, I typically have an primary key ID field which
is int, identity, 1, 1 which works fine as far as I've gone, which I'll
admit isn't all that advanced.


There is obviously an advantage to having a foreign key, because people do
it, but I'm afraid I am too much a learner to know what the advantage is.


Can someone give me a quick explanation of why and/or when its better not to
have the key as a field in the table itself?


Cheers,
Mike Kear
Windsor, NSW, Australia
AFP WebWorks




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