Prepared by Katie Girmus 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 ClassPrimary Key CustomerCustomerID OrderOrderID ProductProductID DistributorDistID Step 1: Define Entity Classes and Primary Keys Business Rules Each order is made by a single customer Each customer can have multiple orders Each customer can have one 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 multiple products A distributor can supply multiple products A distributor has to supply at least one product Each product has to have a distributor

Use 5 symbols 1. 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 CustomerID LastNameFirstNameAddressCityStateZipPhone Customer OrderID CustomerIDOrderDate Order ProductID ProductName 255 Manufacturer 255 Color 50 MSRP Currency Ignition 50 Weight Number QOH Number DistID Number Product DistID Number Distributor 255 Distributor OrderID Number ProductID Number Quantity Number Detailed Orders

Step 4: Create Database (At this point we will begin working with our DBMS system, which will be Microsoft Access)