Re: Newbie question about db normalization theory: redundant keys OK?
Date: Fri, 14 Dec 2007 08:35:35 -0000
"Tony Rogerson" <tonyrogerson_at_torver.net> wrote in message
>> 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));
>> That choice of a primary key is the most obvious one -- use all the
>> columns. Typical rows would look like this:
>> ('Mr. Celko', 'Database 101', 222, 6)
> And half way through term the teacher changed their name to 'Mrs Bunting'
> and now everybody is confused!
> Great example of why you should use an artificial key, I'll remember your
> example for a blog entry I'm writing.
Roy Received on Fri Dec 14 2007 - 09:35:35 CET