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The Data Model for the Great Wall of China 
An Access Database is available.
This is an example of a Bill of Materials Design Pattern and shows how we use the Pattern in practice.
This material is laid out as a Tutorial and supplements our page of Tutorials.
It will help you understand the thinking behind the construction of a simple Data Model.

My Approach
My purpose is to design a simple Datababase for a Toilet, then I will use the Database to create
lists of equipment in each final Product, with partial and total costs.
My first Step is to establish a top-level view from the Head Office.
Then Step 2 defines a Business Data Model which shows how the things we are interested in can be integrated with the Head Office.
Then for Step 3 I obtain a photo that helps me understand a visual perspective of the database functionality,
Then in Step 4 I design A Conceptual Data Model
which is very useful for discussion with business users.
Then I design the Logical Data Model
Finally I create the Physical Model which I use to create the Database.
Step 2 - Review the Business Data Model

Toilet Simple
Step 3 - I start with a Photograph of the Great Wall

Step 4 - Then I find a Drawing of the Great Wall
and helps me to identify the separate parts that I use in my Data Model.

Step 1 - View from Top

Step 5 - Then I design a Conceptual Data Model
for the Diagram in Step 2.
I have added the Toilet Lid and Seat because
they don't appear in the American Standards Diagram.

Img 4 - Parts Diagram
Step 6 - I simplify the Conceptual Data Model
I generalise the Model by replacing specific Components by generic Components.
In this case, it means replacing Lid and Seat, Tank and Bowl by 'Assemblies',
and Trip Lever by 'Components'.

Simple Conceptual Data Model
Step 7 - Then I create a Realistic Logical Model

Img 2 - Parts Diagram


Barry Williams
Principal Consultant
Database Answers Ltd.
London, England
November 22nd. 2018


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