Re: Relation or attribute and why

Gene Wirchenko wrote:

> On 23 May 2006 15:44:15 -0700, "dawn" <dawnwolthuis_at_gmail.com> wrote:
>

>>Gene Wirchenko wrote:
>>
>>>On 23 May 2006 13:44:29 -0700, "dawn" <dawnwolthuis_at_gmail.com> wrote:
>>>
>>>[snip]
>>>
>>>
>>>>In my example, the conceptual data model includes: name, firstName,
>>>>lastName with relationships such that name has-a firstName and name
>>>>has-a lastName.
>>>
>>>     That is part of the logical model.  The conceptual model is the
>>>business statement.
>>
>>The identification of name, lastName, firstName and the relationships
>>among these terms is not part of the business scope and definition, the
>>conceptual data model?  What would the CDM include related to these
>>terms?  I put everything that is conceptual and not directed to a
>>particular implementation model (such as the RM) in the CDM.  Where do
>>you draw the (possibly fuzzy) line?  --dawn

If you are going to interract with the self-aggrandizing ignorants, please, explain their most fundamental errors to them. A conceptual model is a model of information and not solely of data. As such, the term 'conceptual data model' is nonsense that reveals a profound ignorance of the most fundamental definitions.

> Possibly fuzzy, but nonetheless.
>
> Conceptual might fit on a napkin: "We want an E-commerce Web site
> for selling our products. It has to be able to handle North America,
> but we plan to go international, so have the capability to add other
> languages, etc. easily without rewriting large chunks. We want
> someone able to complete an order quickly. Do not forget good
> security. OtherCorp recently had a bad situation, and they are taking
> a kicking. Now is our chance, if we do it right."
>
> Logical gets into the details, but not the implementation.

Gene, that looks more like a high-level requirements statement than a conceptual model. A conceptual model would identify and describe all of the information in the proposed system. A logical model (I prefer "logical design") would specify a formalism that describes the all of the data--"data" being the name for that subset of information suitably encoded for machine processing.

The physical design then specifies on what media and in what structures to record the data. Received on Wed May 24 2006 - 03:13:51 CEST