Re: Newbie question about db normalization theory: redundant keys OK?

David,

Stop trying to divert; you got it wrong; just leave it there.

Here is the original ddl...

CREATE TABLE Schedule
(teacher VARCHAR(15) NOT NULL,
 class CHAR(15) NOT NULL,
 room INTEGER NOT NULL,
 period INTEGER NOT NULL,
 PRIMARY KEY (teacher, class, room, period));

ROWVERSION has nothing at all to do with this I really don't understand why you are trying to deflect the thread to that.

The simple matter of the fact is that on revisting the database with the natural key you obtained (which should not have changed) has changed and points to completely different data.

That is why we need an immutable key.

And... I'm still waiting for you to show me how to put history into celko's schema that would fix the problem where the natural key changes - why oh why are you STILL ignoring that request?

-- 
Tony Rogerson, SQL Server MVP
http://sqlblogcasts.com/blogs/tonyrogerson


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