Answer the following questions concerning Figure 2-22:

a. Where is a unary relationship, what does it mean, and for what reasons might the cardinalities on it be different in other organizations?

b. Why is Includes a one-to many relationship, and why might this ever be different in some other organization?

c. Does Includes allow for a product to be represented in the database before it is assigned to a product line (e.g., while the product is in research and development)?

d. If there is a rating of the competency for each skill an employee possesses, where in the data model would we place this rating?

e. What is the meaning of the DOES BUSINESS IN associative entity, and why does each DOES BUSINESS IN instance have to be associated with exactly one TERRITORY and one CUSTOMER?

f. In what way might Pine Valley change the way it does business that would cause the Supplies associative entity to be eliminated and the relationships around it to change?

SALESPERSON DOES BUSINESS IN TERRITORY PK Salesperson ID Serves + PK Territory ID Salesporson Name Salesperson Telephone Salesperson Fax Territory Name CUSTOMER PRODUCT LINE PK Customer ID PK Product Line ID Customer Name Customer Address Product Line Name Customer Postal Code Submits Includes ORDER PK Order ID Order Date PRODUCT ORDER LINE PK Product ID Product Description Product Finish Ordered Quantity Product Standard Price VENDOR USES PRODUCED IN PK Vendor ID Vendor Name Goes Into Quantity Vendor Address RAW MATERIAL WORK CENTER PK Material ID SUPPLIES PK Work Center ID Material Name Material Standard Cost Work Center Location Supply Unit Price Unit Of Measure Is Supervised By EMPLOYEE WORKS IN Supervises OPK Employee ID HAS SKILL SKILL Employee Name Employee Address PK Skill