ERD Examples

University

We have a university where a Student enrolls in courses. A Student must be assigned to at least one or more Courses. Each Course is taught by a single Professor. A Professor can deliver only one course.

Step 1: Entity Identification

• Student

• Course

• Professor

Step 2: Relationship Identification

• Student is assigned a course

• Professor teaches a course

Step 3: Cardinality Identification

• A student can be assigned multiple courses

• A course can be enrolled by multiple students

• A professor can deliver only one course

Step 4: Identify Attributes

• Student: StudentId, StudentName, StudentAge

• Course: CourseID, CourseName

• Professor: EmployeeId, ProfessorName, EmployeeAge

Note the underlined primary key attribute

Step 5: Create ERD Diagram

MySQL Sample ERD Diagrams

Employee - Department

https://www3.ntu.edu.sg/home/ehchua/programming/sql/SampleDatabases.html