Re: why hierarchy?
From: J M Davitt <jdavitt_at_aeneas.net>
Date: Thu, 27 Jul 2006 03:29:17 GMT
Message-ID: <hqWxg.40608$u11.12953_at_tornado.ohiordc.rr.com>
>
>
> Does the following updated description make sense?
>
> This example models the following things:
>
> A thing named God.
> A person named Adam.
> A person named Eve.
> A person named John whose age is 35.
> A person named Mary whose age is 25.
>
> A thing named Universe.
> A planet named Mars.
> A planet named Venus.
>
> This example also models two hierarchies. In the first hierarchy, John
> and Mary are children of Adam and Eve who are children of God. In the
> second hierarchy, John and Mary are part of Mars and Venus respectively
> which are part of the Universe. Even though John and Mary are in both
> hierarchies, they are not stored redundantly. One way to verify this is
> to display the ID of each thing via the View Menu.
>
>
> In most dbs like Access or SQL Server, the main directory is the first
> window which lists tabled, viewd, forms, reports, etc. In dbd, the main
> directory is named 'dir' and is represented/manipulated like other
> data.
>
> In most dbs like Access or SQL Server, the command "CREATE TABLE
> person" automatically relates table person to the main directory. Dbd
> doesn't. User must specify via (create dir item person). This allows
> the user to control what is displayed in the GUI. Additional info at
> www.dbfordummies.com/Basic/SysData.asp.
>
Received on Thu Jul 27 2006 - 05:29:17 CEST
Date: Thu, 27 Jul 2006 03:29:17 GMT
Message-ID: <hqWxg.40608$u11.12953_at_tornado.ohiordc.rr.com>
Neo wrote:
>>Neo, as far as I can tell, no one understands what simple example the web page depicts ... but nowhere a prose description of wtf all that is supposed to represent.
>
>
> Does the following updated description make sense?
>
> This example models the following things:
>
> A thing named God.
> A person named Adam.
> A person named Eve.
> A person named John whose age is 35.
> A person named Mary whose age is 25.
>
> A thing named Universe.
> A planet named Mars.
> A planet named Venus.
>
> This example also models two hierarchies. In the first hierarchy, John
> and Mary are children of Adam and Eve who are children of God. In the
> second hierarchy, John and Mary are part of Mars and Venus respectively
> which are part of the Universe. Even though John and Mary are in both
> hierarchies, they are not stored redundantly. One way to verify this is
> to display the ID of each thing via the View Menu.
Okay, there are several named things. Some of them are things, some are persons, some are persons with ages, and some are planets. Right so far? And their ID is the bit of magic which glues their characteristics together? (Hmm.. Sounds like Microdata has done this.) CRUD on things shouldn't be tough; you can handle those, right? And there are some hierarchies. Let's treat those as trees.
>
>>There are some ... dir and clsDir ... gui artifacts --
>
>
> In most dbs like Access or SQL Server, the main directory is the first
> window which lists tabled, viewd, forms, reports, etc. In dbd, the main
> directory is named 'dir' and is represented/manipulated like other
> data.
>
> In most dbs like Access or SQL Server, the command "CREATE TABLE
> person" automatically relates table person to the main directory. Dbd
> doesn't. User must specify via (create dir item person). This allows
> the user to control what is displayed in the GUI. Additional info at
> www.dbfordummies.com/Basic/SysData.asp.
>
Received on Thu Jul 27 2006 - 05:29:17 CEST