Read the following scenario. Do not be concerned that you are unfamiliar with the specifics of the setting - that isn't unusual for any systems analyst.Create a list of the entities and level-0 processes for the Data Flow Diagram. Also, create a list of the entities and their primary keys for the Entity Relationship Diagram.

The Smalltown Music & Video Company advertises in a variety of magazines. Most orders are submitted by magazine subscribers who complete and send coupons to the mail order company. All mail arrives at the receptionist's desk. The receptionist sorts and distributes the mail to the appropriate departments.Mail orders and letters requesting order cancellations are forwarded to an order-entry clerk in the sales department.

The order-entry clerk initially checks the availability and the price of the ordered items and, if necessary, mails a back-order notice to the customer stating that there may be multiple shipments for this order.This clerk also takes orders from customers directly by phone and forwards all fillable orders to the credit-clerk. When the order-entry clerk receives a letter requesting an order cancellation (or a cancellation by telephone), the status of the order is first determined. If the customer order has not been processed, the order-entry clerk informs the warehouse that the order should be canceled and then informs the customer that the cancellation has been completed.

When fillable orders are received by the credit clerk, the customer's credit status is checked. Orders are approved and an order-confirmation letter is sent to those customers with good credit standing. Customers with bad credit standing are sent a payment-overdue notice requesting pre-payment.The credit clerk forwards approved orders to the warehouse.

The warehouse fills the approved order and updates the inventory availability. An invoice is sent with the packaged order to the customer, and a shipping notice is sent to the accounts receivable department. The invoice may contain data from several orders as back-orders are shipped.Accounts receivable bills the customer for the products shipped. This department also maintains the invoice data files, updating them to reflect charges or payments received. Payments are received in the mail and delivered to accounts receivable by the receptionist. A payment receipt is sent to the customer.