(Exercise 3.24 from the book of Elmasri and Navathe, Addison-Wesley)

Consider the ER diagram of the following figure. Assume that an employee may work in up to two departments, but may also not be assigned to any department Assume that each department must have one and may have up to three phone numbers. Supply on this diagram participation and cardinality constraints and (min, max) constraints. State clearly any additional assumptions you make. Under what conditions would the relationship HAS_PHONE be redundant in the above example? An ER diagram for a database that keeps track of company and employee phones