An Engineering Department has only two types of employees. An employee is either an ENGINEER or a SECRETARY. The attributes of ENGINEER include Employee_ID, Name, Address and Engineer Type. The attributes of SECRETARY include Employee_ID, Name, Address and Typing Speed. Each Engineer may be assigned to one PROJECT with the Project_ID, Start date and Completion date as attributes. A project must have at least one engineer assigned.

Answer the following questions.

Q1) Justify why it is better to use Enhanced Entity-Relationship diagram than Entity-Relationship diagram in this case?

Q2) Describe the completeness constraint and disjointness constraint for the above situation.

Q3) Use any drawing tool to draw an enhanced ERD for the above situation. Attributes of supertype and subtypes, subtype discriminator, and the disjointness constraint / completeness constraintshould be included in your EERD.