Re: cdt

"mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message news:40c30e76$0$563$e4fe514c_at_news.xs4all.nl...
> Alan wrote:
> > Looks good, though I propose some very minor changes
>
> Thank you. It is in preparation. I sent it by accident and cancelled it
> a few minutes later. You must have cought a propagation.
> I'll look at your comments anyway.
>

Ooops! It looks like I emailed to you diectly, instead of posting, so here is the essence of what I sent:

Looks good, though I propose some very minor changes (in line) marked with =====>>>>>

"mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message news:40c30358$0$568$e4fe514c_at_news.xs4all.nl...
> [change management]
> The organization of data within a database can and will
> change with circumstances, and the database should provide
> facilities for changing this structure with minimum
> inconvenience.

=====>>>>> "minimum inconvenience" is kind of vague. This definition sort of restates one of the basic conditions needed for an RDBMS: the notion that the underlying structure can be changed without affecting what is already stored. IOW, for example, you can add a column to a table without losing what is already there. Don't know how I'd rephrase it...

> [data model]
> data models are artificial constructs and can

=====>>>>> I would change "can never" to "may not". Sometimes they do represent completely.

> never completely represent the true nature of information, and goes on
> to provide various philosophical examples of recategorization.
> ... these categories already
> exist, to some degree, in the way information is handled. Databases
> don't exist in vacuo; they're fed (and consulted) by users who would
> have some system of mental categorization even if they were shuffling
> everything around with paper and pencil.
>
>> [information]
> 0.a. synonymous to data

=====>>>>> The term is sometimes used this way, but in our theoretical world, I believe it is important to make the destinction as you have below in 0.b. I would leave out 0.a for clarity's sake.

> 0.b. data in context, data with meaning.
> (Implies a definition of data as being without context,
> whithout meaning - see data)
> 1. new data to the receptor.
> 2. available data, relevant to some decision or action.
> [key]
> A value, used to identify something.

=====>>>>> "uniquely (as in PK, CK) identify or relate (as in FK)"

>>
> [table, row, column]
> table: A sentence that has not yet been uttered,
> because it relates unknown values.
> row: A statement of fact, as an utterance of the "meta" sentence
> described above.
> column: any piece of utterable information.

=====>>>>> I see where you're going, but unless the following is understood, it could be confusing. Okay, this one isn't minor Trying to keep it general irrespective of normal form, but still giving it context:

Table: A collection of rows and columns. Row: A collection of attributes.
Column: An attribute of an entity.
Entity: The subject about which the table is concerned.

I know this is slightly reflexive, but as you have already indirectly specified, these terms are best understood as they relate to each other. You could probably combine the two different takes on this.

>
Received on Sun Jun 06 2004 - 15:12:13 CEST