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Method for Database Design

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

This is the General Approach which is a structured method 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..
    The situation to be modelled is :
    A car dealership with a few branch car lots in different locations.
    The Inventory usually consists of a few dozen cars, (new, used, all brands) in stock.
    An online inventory database is required 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.
    The starting-point is 4 proposed entities :
    - BRANCH      : location, contact info.
    - INVENTORY   : vehicle available for sale, its branch location, and the salesperson to contact.
    - SALESPERSON : contact info, and the branch the person belong.
    - VEHICLE     : physical descriptions about a vehicle

    Barry Williams
    Principal Consultant
    Database Answers

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