Re: Separate PK in Jxn Tbl?
Date: Tue, 29 Jan 2008 20:27:43 -0800 (PST)
On Jan 29, 4:41 pm, "David W. Fenton" <XXXuse..._at_dfenton.com.invalid>
> Marshall <marshall.spi..._at_gmail.com> wrote innews:email@example.com
> > On Jan 28, 3:31 pm, "David W. Fenton"
> > <XXXuse..._at_dfenton.com.invalid> wrote:
> >> >> And it all leaves aside the question of how you know that
> >> >> husband/wife/date is always going to be unique. I think that
> >> >> on any given day in the US, there are plenty of marriages in
> >> >> which those three values will be identical. You could add
> >> >> place. But then, in large cities, that might not be enough. So
> >> >> use Postal Code in place of place, and that might do the
> >> >> trick, although in large cities that might not do it, either.
> >> > Huh? You think there are some pairs of people who are getting
> >> > married more than once on the same day?
> >> People with the same names could be getting married on the same
> >> day in the same place, yes.
> > The schema doesn't have any names in it.
> But the real-life entities do, so your schema must allow it, or it's
> an incorrect schema (for the application in question).
You are slipping seamlessly between the concept of a person and the person's name; they are not the same.
Marshall Received on Wed Jan 30 2008 - 05:27:43 CET