Re: Logical Data Model

"dawn" <dawnwolthuis_at_gmail.com> wrote:

[...]

>>From Fabian Pascal Papers, FP02, December 2003, Updated February 2005
>"Un-muddling Modeling" p.13.

hmmm... I am trying to understand these three sentences, and I am serious about it. (english is not my first language, so please try to be patient with me... :)

>"So we have three kinds of models which ought not to be confused.

ok, no problem, jumping ahead: The three models not to be confused are

  (1) logical model
  (2) conceptual model
  (3) data model 

> A (1) logical model is the formal representation in the database as seen
>by users of the (2) conceptual model, the meaning of the database as
>understood by users; and is the meaning of the database as understood
>by the DBMS.

Here I am pretty much at a loss. At least it seems to me, that, grammatically, the notion of a "database" must have been defined *beforehand*.

I am going to try to separate some parts of this sentence:

  (1) "logical model"

 seems to be defined as:

(*) "the formal representation in the database as seen by users

          of the conceptual model"

 and seems also be defined as:

(**) " the meaning of the database as understood by the DBMS".

Furthermore,

  (2) conceptual model

seems to be defined as

(***) "the meaning of the database as understood by users"

>A (3) data model is the formal translation mechanism of
>the latter to the former."

What is the latter? The (2) conceptual model? What is the former? The (1) logical model? Thus, trying to rephrase:

(****) "A (3) data model is the formal translation of the

             (2) conceptual model to the (1) logical model."

Is this correct?

I really do not understand sentences (*), (**), (***), and (****).

With kind regards
Matthias Kläy

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www.kcc.ch