Data abstraction is an important concept in database systems, and something that we

have discussed throughout the course.

a$.(10$ Points$)$ Give a description of each of three abstraction levels of a database

system, and describe someone who would be concerned with that layer $($i$.$e$.$

what types of users are each layer designed for$).$

b$.(10$ Points$)$ Give a description of the three layers of abstraction within a

database application, and how you enforce this abstraction within your

application.