Subject: Customers, Sellers and Books
Hello Barry,
I have been assigned a project to create a Microsoft Access database which will be based on a company which sells books online. 
I obviously first need to create an entity relationship diagram but I am struggling as to how to determine a customer. 
This is because as the brief states "the company specialises in remaindered and second-hand textbooks. 
The company buys surplus books from publishers but also buys individual books from students. 
The books are advertised and sold via the company's website." 
The system I need to create will need to record the basics of recording sales but will also need to produce invoices etc. 
However I am struggling in how to define a customer as a student could also be a customer which sells a book to the company ? 
And so obviously I cannot have two tables one for students and one for customers as this runs the possibility of duplicating the data.
Any help will be greatly appreciated.
Kind regards,
Michael