Consider a MAIL_ORDER database in which employees take orders for parts from customers. The data requirements are summarized as follows:
■ The mail order company has employees, each identified by a unique employee number, first and last name, and Zip Code.
■ Each customer of the company is identified by a unique customer number, first and last name, and Zip Code.
■ Each part sold by the company is identified by a unique part number, a part name, price, and quantity in stock.
■ Each order placed by a customer is taken by an employee and is given a unique order number. Each order contains specified quantities of one or more parts. Each order has a date of receipt as well as an expected ship date. The actual ship date is also recorded. 

Design an entity–relationship diagram for the mail order database and build the design using a data modeling tool such as ERwin or Rational Rose.