Question

A nonprofit organization depend on a number of different types of persons. The system needs to maintain the following data for all persons: SSN, Name, Address, City, City, State, Zip, and email. There are three types of persons: employees, volunteers, and donors. Employees have a unique Date Hired attribute, and volunteers have a distinct Skill attribute. Donors donate items. Item has attributes like Item ID and Description. A donor may donate multiple items. An item may be associated with no donor or one donor.

Occasionally, there are persons other than the three types (employees, volunteers, and donors). In other words, a person may not belong to any of these three types. Also, a person may belong to two or more of these types (e.g., a person is an employee and also a donor). Create the ERD for the system in Microsoft Visio.

Answer 1

ERD

• Employee, Volunteer and Donor are subclasses of Person.
• The primary key of Person is SSN and it is given as the foreign key in each subclasses.
• This is a incomplete overlapping relationship because there are persons other than the three types and a person may belong to two or more of these types .
• A donor may donate multiple items. An item may be associated with no donor or one donor. S this relationship is optional one to mandatory many.
• All the entities, attributes, keys, relationship and cardinalities are shown using crow's foot notation in the ERD.