Order Processing System

A systems analyst has noted the following points in an interview with a user in the order processing department.

Orders are received from customers. Customer may place many orders in the year. Orders are usually for multiple products. When the ordering clerk receives an order from a customer, he or she will check whether the order is complete or not. If not, the order will be returned to the customer. Then the ordering clerk will check whether the customer is new. If the customer is new, the customer information will be saved.

For the complete order, the ordering clerk will determine the discount for the order according to the following rules. We normally give a customer 5% discount if both of the following conditions are fulfilled:

(a) the unpaid balance on the account is less than $10,000

(b) all invoices outstanding are less than three month old.

If one of these conditions is violated, the discount allowed is 2%. No discount will be given if both conditions are violated. Customers who have been trading with us for more than 2 years are allowed an additional 2% discount provided that neither of the above conditions is violated.

After the discount is determined, the order will be saved. The ordering clerk will acknowledge receiving the complete order to the customer and provide the order number to the customer. A picking list will also be generated and sent to the warehouse.

At the end of the week an invoice is issued. This lists the orders placed in that week and invoice total for all the orders placed in the week. The invoice is sent to the customer. The invoice will also be saved.

Customer payments are recorded in a spreadsheet. Some customers send cheques that cover many invoices. On some occasions a customer part-pays the invoice.

1. List the events that need to be handled by the order processing department.

2. Construct an entity-relationship model from the information recorded in the interview. Break down the many-to-many relationships. Underline the key attributes and provide all the attributes for each entity which you think are important to fulfill the function of the operation.

3. Draw logical data flow diagrams that model all the major functions of the operation.

4. Use decision table to specify how to determine the discount for an order