DirtBike Order Database– ER Diagram

Prepared by

(Rahul Dhami)

Fall 2012

Step 1: Define Entity Classes and Primary Keys

Step 2: Define Relationships Among Entity Classes

Step 3: Define Fields for each Relationship

Step 4: Create Database

Designing Databases with Entity Relationship Diagrams

Entity Class Primary Key

Customer Customer ID

Order Order ID

Product Product ID

Distributor Distributor ID

Step 1: Define Entity Classes and Primary Keys

Business RulesEach order is made by a single customer

Each customer can have multiple orders

Each customer can have on order

Customers can be in your database without any orders

Products can be listed in your database but not purchased

Orders cannot be blank

Orders can have more than one (multiple) products

A distributor can supply multiple products

A distributor has to supply at least one product

Each product has to have a distributor

E-R Diagrams

Use 5 symbols1. Rectangle – entity class

2. Dotted line – relationship

3. | - single relationship

4. 0 – zero/optional relationship

5. Crow’s foot () – multiple relationship

PRODUCT

CUSTOMER ORDER

Step 2: Define Relationships Among Entity Classes

DISTRIBUTOR

Detailed Orders

Step 3: Define Fields for each Relationship

Customer ID LastName FirstName Address City State Zip Phone

ENTITY

Product ID Product Name

Manufacturer MSRP Ignition Weight QOH Distributor ID

Product

Order ID Customer ID Order Date

Order

Distributor ID Distributor

Distributor

Order ID Product ID Quantity

Detailed Orders

Step 4: Create Database

(At this point we will begin working with our DBMS system, which will be Microsoft Access)