Create the ERD for the following scenario:

Trek Sports wants to keep track of customer purchases. For each product there is a product number (which is unique), product name, description, and price. Each invoice has a number (which is unique), and date. An invoice can include many products, and a product can appear in multiple invoices. An invoice must have at least one product, but a product may never be sold (so may not appear in any invoices). When a product is sold, the database should keep track of the quantity sold.

An invoice is written by a sales rep. A sales rep is identified by a unique number. The database should also capture the name and phone number of each sales rep. Each sales rep can write many invoices, but each invoice is written by a single sales rep. While an invoice must have a sales rep, a sales rep can be new and may not have written any invoices.

An invoice is written for a single customer. However, each customer can have many invoices. In order to be in the database, each customer must have at least one invoice. Also, each invoice must have a customer. For each customer, the database should record an ID (which is unique), name, address, and phone number.