What is a Use Case Model? discuss what is the difference between the COUNT aggregate function and the SUM aggregate function? Give an example.

1) What is a Use Case Model? Review the following diagram:

Use Case Diagram (Links to an external site.)http://www.utm.mx/~caff/doc/OpenUPWeb/openup/guidances/concepts/resources/atm_uc_diagram.GIF

What information can you obtain from the diagram? Be specific. What differences do you see between a business process model and a use case diagram?

2) In a minimum of 100 words, discuss what is the difference between the COUNT aggregate function and the SUM aggregate function? Give an example.