Re: Entity vs. Table
Date: Thu, 17 Jun 2004 09:17:50 -0400
"Alfredo Novoa" <alfredo_at_ncs.es> wrote in message
> On Tue, 15 Jun 2004 09:23:35 -0400, "Alan" <alan_at_erols.com> wrote:
> >> The Relational Model says nothing about the physical level.
> >I am talking about taking a completed relational model design and
> >implementing it. You know, I've designed all the tables and now I'm
> >SQL to build them in the RDBMS.
> SQL mixes the logical and the physical levels, but the most part of
> the physical design is created by the SQL DBMS automatically.
> It is perfectly valid to have redundancy in the physical tables.
> >> But where is the rule?
> >> A double oval says that an attribute is derived but it says nothing
> >> about the derivation rules.
> >> You are losing the business requirements.
> >No one said that the ERD models ALL business requirements.
> But you said that it can represent most of them, what is clearly
> > For the 50th
> >time, it models relationships among the data.
> Only a very little part of the requirements, and it does that worse
> than The Relational Model.
> There are not precise definitions for "entity" and "relationship". The
> distinction is arbitrary. The ERD is a backward step and heavily
I guess the often ranked number 1 university in the U.S. (by U.S. News & World Report) in I.S. grad programs is wrong and you are right. Use whatever tools you want to use, just leave me alone. Received on Thu Jun 17 2004 - 15:17:50 CEST