Re: Basic question?What 's the key if there 's no FD(Functional Dependencies)?

<saturnlee_at_yahoo.com> wrote in message
news:1162158876.794350.29460_at_f16g2000cwb.googlegroups.com...
> I have a basic question.
> Suppose there are 3 attributes: A,B and C.
> And there are no FD(trivial and non trivial )
>
> What 's the key for it? ABC or nothing???
>

A relation with at least one attribute *ALWAYS* has at least one FD. Here are some of them for your example:

{ABC} --> A
{ABC} --> B
{ABC} --> C
{ABC} --> {ABC}

Note that all of the FD's are trivial. Received on Wed Nov 01 2006 - 08:40:03 CST