Re: What is that "more" that makes E-R model truly independent ?
Date: Tue, 24 Jul 2007 03:52:32 -0700
Message-ID: <1185274352.210447.62130_at_d55g2000hsg.googlegroups.com>
On 24 jul, 03:08, beginner16 <kaja_love..._at_yahoo.com> wrote:
> I just started learning a little about E-R model. I realize the E-R
No, we only can represent some aspects of a database with E-R
drawings.
> But as I stated before, E-R model diagram would be the same no matter
It is not.
>But what is that
It is more vague and more imprecise. Being even more vague we could be
even more independent, and saying nothing we achieve complete
independence :-)
For instance this is THE diagram of Alfredo's Universal Data Model:
Alfredo's Universal Data Model diagram would be the same no matter
which system we want to build. Alfredo's Universal Data Model rises
independence to unprecedent levels :-)
> 2)
> hello
> model was created so that we can represent DB at the conceptual level,
> and as such DB is presented independently of the underlying logical
> DB design.
> if logical DB implementation is hierarchical or relational. For that
> reason I assume that ER modeling is more than just using symbols for
> entity, attributes, relationships
> "more" that makes E-R model truly independent of logical DB
> implementation ?
.
> Does relational model also have its own graphical symbols defined
> ( for graphical representation ) or do we always need "outside"
> diagrams ( E-R model, Bachman's model etc ) in order represent it
> graphically?
No.
Regards
Alfredo
Received on Tue Jul 24 2007 - 12:52:32 CEST