Re: RM VERY STRONG SUGGESTION 4: TRANSITION CONSTRAINTS
Date: Thu, 9 Sep 2010 04:10:33 -0700 (PDT)
Message-ID: <ad4048b1-3d41-40d3-9638-aa93688f4232_at_f26g2000vbm.googlegroups.com>
> Every tuple has a superkey consisting of all prime components;
I imagine that by *components* you mean attributes. A candidate key
is simply a subset of a superkey.
> every
> key is a surrogate; therefore every tuple has a surrogate. A
> surrogate for what?
Stop using the false premise that a surrogate must be a superkey, and
it will make total sense.
> For an object in the microworld being modeled.
It does remind me of a Star Trek quote...
> If that doesn't constitute a mapping, then perhaps you can enlighten
> me as to what does.- Masquer le texte des messages précédents -
The answers given to you by paul c and BB are crystal clear. paul c
is correct you *do* have mental blocking about that.
Received on Thu Sep 09 2010 - 13:10:33 CEST