EntityRelationship Modeling

Exercise 1:

Create an ER model for the following descriptions of a database hosting companies:

Each company operates one or more departments, and each department is operated by one company.

A company has a unique companyName, an address, and a telNo (telephone number). A department has a unique deptName, a location, and a telExtention (telephone extension number).

Each department employs one or more employees, and each employee works for one department.

An employee has a unique employeeNo, a name, a position, and a salary.

An employee may or may not support dependents, and each dependent is supported by one employee.

A dependent has a unique depNo, a depName, and a dateOfBirth.

Exercise 2:

Create an ER model for the following descriptions:

Professors, students, and courses have the following unique numbers respectively: professorNo, studentNo, and courseNo.

Each professor can teach from 1 to 6 courses.

A student can take any number of courses.

The capacity of each course is 25 students.

A professor can advise up to 5 students.

An associate professor can inspect up to 3 assistant professors.