Method for Database Design

The first cut for the Data Model is shown below, and becomes the Database design.

This Structured Method is a general approach to establish the FACTS :-
1) Define the Area of Interest,(e.g. Car Sales).
2) Define the "Things of Interest",(e.g. Cars), in the Area of Interest.
3) Analyze the Things of Interest and identify the corresponding Tables.
4) Establish the relationships between the Tables.
5) Determine the characteristics of each Table,(e.g. a Car has a Manufacturer).
6) Obtain a small set of Sample Data.
7) Confirm the first draft of the Database design against the Sample Data.
8) Obtain from the users some representative enquiries for the Database.
9) Review the Results of Steps 1) to 8) with appropriate people, such as Users, Managers,
Development staff, etc. and repeat until the final Database design is reached.

Things of Interest in this Area are shown as Entities in the diagram :-

Cars, Car Manufacturers, Customers, etc..

Here is user's proposed design :
We are a car dealership with a few branch car lots in different part of the state(or city).
We have a few dozen cars of variety(new, used, all brands) in stock.
We are doing a online inventory database to attract and inform customers. 
It will allow users to access all our vehicles that are for sell, and view related information like detail, location, contact person.
I have 4 proposed entities right now:
-VEHICLE     : physical descriptions about a vehicle
-INVENTORY   : vehicle available for sale, its branch location, and the salesperson to contact.
-SALESPERSON : contact info, and the branch the person belong.
-BRANCH      : location, contact info.
Please give me your comments. I'd really like to go on to the next step some time.

Barry Williams
February 5th. 2001
Principal Consultant
Database Answers