13-22 Martin Shoes, Inc. (Planning a Database Using REA and E-R Methodology) Martin Shoes, Inc., manufactures and distributes orthopedic footwear. To sell its products, the marketing department requires sales personnel to call on the shoe retailers within their assigned geographic territories. Each salesperson has a laptop computer, which he or she uses to record sales orders during the day and to send these sales order to Martin's network nightly for updating the company's sales order file. Each day, warehouse personnel review the current sales order in its file, and where possible, pick the good and ready them for shipment. (Martin ships goods via common carrier, and shipping terms are generally FOB from the shipping point.) When the shipping department completes the shipment, it also notifies the billing department, which then prepares an invoice for the customer. Payment terms vary by customer, but most are "net 30." When the billing department receives a payment, the billing clerk credits the customer's account and records the cash received. Requirements: 1. Identify the resources, events, and agents within Martin's revenue process. 2. Develop an E-R diagram for this process. 3. With a particular DBMS is mind, design the tables for this revenue process. Note that you will need tables for each resource, event, and agent, as well as tables for each many-to-many relationship. This has me utterly confused. I even read the chapters and still haven't been able to figure it out. Someone help?