Re: 3NF question
From: DA Morgan <damorgan_at_x.washington.edu>
Date: Sat, 08 Jan 2005 08:50:56 -0800
Message-ID: <41e00e43$1_4_at_127.0.0.1>
Date: Sat, 08 Jan 2005 08:50:56 -0800
Message-ID: <41e00e43$1_4_at_127.0.0.1>
Elves wrote:
> Hello
>
> I am still not sure about meaning of 3NF
>
> Let's say I've got a table, named USERS:
>
> Id Login Pass Description
>
> Id was selected as a key, but login has to be unique, so it's also a
> key. There are dependencies:
>
> Id -> Pass, Description
> Login -> Pass, Description
> Id -> Login
> Login -> Id
>
> is this 3NF or should it be decomposed to two tables like this:
>
> Id Login
> Login Pass Description
>
> thanks in advance, Elves
In your example ... ID is without purpose which is pretty much the case for any column misnamed ID. Try this instead:
LOGIN_ID
LOGIN_PWD
If you want to get a bit more complete add:
EXPIRATION_DATE
STATUS_FLAG
-- Daniel A. Morgan University of Washington damorgan_at_x.washington.edu (replace 'x' with 'u' to respond)Received on Sat Jan 08 2005 - 17:50:56 CET