SEU Operating Systems Essay

1-Considering the following ER-Diagram, answer the following questions:

a) What is the main role of an ER diagram in data modelling?

b) How many courses each student can have?

c) What is the relationship degree between the entities?

d) Is there an associative entity, if yes can you name it?

e) What is uniquely identifying the student entity table (Primary Key)?

2- Draw a class diagram showing classes, attributes, operations, and relationships. If you believe that you need to make additional assumptions, do so.

Scenario: several employees are working at a company. The attributes of the employees include the employee ID, Employee Name, address, DOB. The company is running different projects. Projects attributes include the project name, the start date and end date.

Each employee may work on one or more projects or may not be assigned to a project. However, each project must be assigned to at least one employee.

• Make sure that you identify the PK for each class
• Your diagram must include Associative class
• Implement Generalization

3- The following INSTRUCTOR relation shows the information of instructors and the training sessions they offer. Each instructor can give any session at a chosen date. Why INSTRUCTOR relation is not in 2NF? How can you convert it be in 2NF?

4- The following CAR relation is in 3NF. What an attribute that if added to the relation, it would make it not in 3NF? Justify your answer.

CAR (CAR MODEL, CAR_YEAR, DEALERSHIP). Assume that each car model is only sold by one dealership.