Re: Navigation question
Date: 22 Feb 2007 18:05:56 -0800
Message-ID: <1172196356.504564.212670_at_v33g2000cwv.googlegroups.com>
On Feb 22, 6:34 pm, mAsterdam <mAster..._at_vrijdag.org> wrote:
> dawn wrote:
> > mAsterdam wrote:
> >> dawn wrote:
> >>> In another thread "navigation" is again mentioned as undesirable.
>
> [snip]
>
> >> Nothing good, nothing bad here, just: navigation is something that
> >> does not exist within the RM.
>
> > Right.
>
> [snip]
>
> >> 'From a fk in a child to a parent tuple'
> >> is at best metaphor (and btw. borrows hierarchical terms).
>
> > Do these terms properly communicate so that you know what I mean,
>
> No.
Let's say you are looking at a report, on paper, showing a set of attribute names and values for a Person with personId="77777" fmName="Danni Lynn" mother="11111". You put your finger on Danni Lynn's mother value. Then you realize that on that same piece of paper there are more values from the Person relation listed, including one with personId="11111" and fmName="Anna Nicole".
> > or is there some better way to say this?
>
> AFAIK not yet. Please stay focused and don't state your questions
> as loaded as this.
> >> You want to discuss navigation? Ok. The RM will not proliferate
> >> vocabulary. Furthermore, the first thing people will associate
> >> it with is the physical level hidden by the DBMS. You have clearly
> >> stated that that is not what you want to talk about.
>
> > Correct.
>
> >> Let's go navigating the database - not at the physical level, but
> >> somewhere else; 'Navigating foreign keys', example:
>
> [snip example - people who want to read it should navigate up the nntp
> tree]
>
> > Yes. My understanding from responses to date is that thie type of
> > navigation is not considered bad and not considered logical
> > navigation, but more of a user interface conceptual navigation. Each
> > user event permits us to start anew so that the code does not navigate
> > the database, only the user does. So, while the physical is at a
> > lower level than I want to discuss navigation, user-event driven
> > "navigation" of a database is at a higher level.
>
> The physical stuff is lower, so this must be higher, right?
> Well, I do not think so. Earlier, maybe, part of it.
>
> (For the RM-only zealots out there I am thinking of the
> place in time in the whole of the construction/growth of
> databases, not just the moment from which all is clear and downhill
> sliding after - after the specs have been signed, sealed and
> delivered. Yes, this is database theory. RM-only zealots are stupid,
> not just ignorant: "Men are born ignorant, not stupid. They are made
> stupid by education." -- Bertrand Russell
> )
> As soon as someone tells me something is 'higher level'
> I think: on which stairway?
>
> Higher level - than what? why is it higher? How do you measure that?
Add 8 "User Layer" to the OSI layers. My questions are regarding layer 7, where "logical navigation" of a database might take place. Does that work for you? --dawn Received on Fri Feb 23 2007 - 03:05:56 CET