We would like to design a database to maintain information about hospital staff, including doctors and nurses, and patients at the hospital. The information we need includes:
* Staff, including their names, addresses and social-security numbers.
* Patients, including their names, addresses, and the name of their insurance company.
* Patients are each assigned to a ward (room).
* Those staff who are nurses are assigned to zero or more wards. Each ward has at least one nurse assigned.
* Those staff who are doctors are assigned to zero or more patients. Patients may or may not have a doctor assigned, and they may have more than one doctor. Patients in the same ward may have different doctors but will always have the same nurse(s).
Specify an entity-relationship diagram for this database. Don't forget to underline key attributes and include arrowheads indicating the multiplicity of relationships. Note that there is no single right answer to this question, although some answers may be better than others.