Re: Advanced SQL
Date: Fri, 07 Sep 2007 13:59:45 -0000
On 7 sep, 15:43, Jon Heggland <jon.heggl..._at_idi.ntnu.no> wrote:
> Quoth Evan Keel:
> > "David Portas" <REMOVE_BEFORE_REPLYING_dpor..._at_acm.org> wrote in message
> >> Call me picky but I am not entirely comfortable with that U.Texas site,
> >> even though it's a commendable effort overall.
> >> "The definition of second normal form states that only tables with
> >> composite primary keys can be in 1NF but not in 2NF"
> > They have it right here. All non-key attributes must be dependent on the
> > full key. Only applies to tables with keys composed of multiple columns>
> No. There may be dependencies where the left side is empty.
> But it's a
> common mistake. If I remember correctly, one of my database textbooks
> "proves" that any relvar with just two attributes is automatically in BCNF.
- Jan Hidders