Re: Identifying candidate keys and primary keys

On Apr 13, 7:05 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> <noagbodjivic..._at_gmail.com> wrote in message
>
> news:fc37fe0e-476b-4a0b-8396-ab81c9a5f4a1_at_u69g2000hse.googlegroups.com...
>
>
>
> > Hello guys, this one is for one of my assignments. I want explanations
> > and hints only.
>
> > I'm still confused with the concepts of candidate keys and primary
> > key. We have a patient medication form from an hospital with these:
>
> > Heading: Patient number, Full name, Bed number, Ward number, Ward
> > name.
> > Then a table with this columns: drug number, name, description,
> > dosage, method of admin, units per day, start date, finish date.
>
> > I have to find all the candidate keys and primary keys. I think
> > candidate keys are the minimal superkeys.
>
> > I have found {Patient number, Ward number, Ward name}. I have excluded
> > {Patient number, Ward number, Ward name, Full name} and {Patient
> > number, Ward number, Ward name, Full name, Bed number} which are also
> > superkeys but contain more attributes.
>
> Can a patient be in more than one ward (at the same time)?
>
> > This means that I have found only one candidate key, and this is also
> > the primary key I have found (a composite).
>
> > Since the question was "identify all the candidate keys" I thought
> > maybe I dont really understand the concepts...
>
> http://en.wikipedia.org/wiki/Candidate_key
>
> > thanks for any help.

Brian, I don't really know...

I have been looking at how hospitals work here in US. From what I have learned online, I don't think it's possible to have a patient in multiple ward at the same time (and I can't confirm).

Also from what I have learned it seems like the ward names are unique in hospital. It probably means that a ward number assigned to a name is also unique. So that when we take a name, we have the number. But I can't confirm that either, I have found all this by searching online... Received on Sun Apr 13 2008 - 22:02:41 CEST