1. Order Database – ER Diagram
Prepared by
Shelbi Hood
Sophomore- Fall 2016

2. Designing Databases with Entity Relationship Diagrams
Step 1: Define Entity Classes and Primary Keys
Step 2: Define Relationships Among Entity Classes
Step 3: Define Attributes for each Table
Step 4: Create Database

3. Step 1: Define Entity Classes and Primary Keys
There is not a limit to the number of orders a customer may place. Each customer can have one order, multiple orders, or be in your database without any orders. Each order is made by a single customer. Orders must have at least one product. Orders may have multiple products. The same product could be sold through many orders. Products can be listed in the database but not ordered by a customer.
Entity Class
Primary Key
CUSTOMER
CustomerID
ORDER
OrderID
PRODUCT
ProductID
ORDERITEM
OrderID ProductID
Business Rules
1. Customer may have many orders.
2. Customers may have no orders.
3. Order can have one customer.
4. Order must have a customer.
5. Order must have at least one product.
6. Order can have many orders.
7. Product can have multiple orders.
8. Product may not appear on any order.

4. Step 2: Define Relationships Among Entity Classes
CUSTOMER
ORDER
PRODUCT

5. Step 3: Define Attributes for each Table
CUSTOMER
CustomerID
FirstName
LastName
Address
Major
Location
Gender
ORDER
OrderID
CustomerID
OrderDate
PRODUCT
ProductID
ProductName
Price
BatchSize
Description
ORDERITEM
OrderID
ProductID
Quantity

6. Step 4: Create Database