1. Order Database – ER Diagram
Prepared by
Channing Downing
Spring 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
Business Rules
1. Customers can have multiple orders
2. Customers may no orders
3. Each order has one customer
4.Each order must have a customer
5. An order can have multiple products
6. An order must have 1 product
7. A product can have multiple orders
8. A product that has no orders

4. Step 2: Define Relationships Among Entity Classes
Customer
Order
Product

5. Step 2: Define Relationships Among Entity Classes
Customer
Order
ORDERITEM
Product

6. Step 2: Define Relationships Among Entity Classes
Customer
Order
ORDERITEM
Product

7. Step 2: Define Relationships Among Entity Classes
Business Rules
1. Customers can have multiple orders
2. Customers may no orders
3. Each order has one customer
4.Each order must have a customer
5. An order can have multiple products
6. An order must have 1 product
7. A product can have multiple orders
8. A product that has no orders
Customer
3 4
Order 7 8 6 5
Product
Won’t need this slide

8. Step 3: Define Attributes for each Table
CUSTOMER
CustomerID
LastName
FirstName
Address
ORDER
OrderID
CustomerID
Product
SerialNumber
PRODUCT
ProductID
AmountOrdered
OrderID
ORDERITEM
OrderID
ProductID

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

10. (DBMS system - Microsoft Access)
Step 4: Create Database
(DBMS system - Microsoft Access)