ENTITY-RELATIONSHIP DATA MODEL - Database Design and Development: An Essential Guide for IT Professionals - page 229

1. Each course offered may be taught in different classes. For example, the Data-
base Design course may have a Tuesday night class and a Thursday night class.
2. A faculty member may teach one or more classes.
3. Different faculty members may be assigned to teach different classes of the
same course.
4. Each faculty member decides on the number of exams for the class he or she
teaches. Student scores are assigned for each type of examination or test.
5. A specific textbook is assigned to a course.
6. A student may be enrolled in one or more courses.
7. Each class meets in the same room during a semester.

Figure 7-22 presents an ERD for the given information requirements. Note that
the diamond-shaped relationship notation is not shown in this ERD. This is an
acceptable practice. Although the relationship notation is not explicitly shown, the
implied relationships are expressed by the lines connecting entity type boxes.

Highlights of Sample ERD

Study the ERD carefully. Note all the entity types and observe the relationships.
What do the cardinality indicators represent? Are there any composite attributes?
Go back to the list of components and notations shown in Figure 7-21. How many
of these can you identify in Figure 7-22?
Compare the information requirements with the ERD. Does the ERD reflect the
information requirements adequately?

Speczn FacultyID

TypeID

FacltyName

ExamName

EXAM TYPE

FACULTY

Phone

1 1

*

MinScore

Department

*

CourseNo

Score

CLASS

GRADE

ClassNo

*

1

*

RoomNo

*

1

CourseNo

COURSE

CourseDesc

*

Credits

SocSecNo

Author

Price

1

1

StudntName

I SBN

STUDENT TEXTBOOK

Major Title

Figure 7-22 ERD: university teaching aspects.