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Re: why hierarchy?

From: Neo <neo55592_at_hotmail.com>
Date: 26 Jul 2006 19:14:01 -0700
Message-ID: <1153966441.547338.228570@h48g2000cwc.googlegroups.com>


> 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.

> 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 Wed Jul 26 2006 - 21:14:01 CDT

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