Create an ER diagram for a university database system that includes entities, attributes, relationships, and cardinality constraints

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Create an ER diagram for a university database system that includes entities, attributes, relationships, and cardinality constraints. Provide a brief explanation of your design choices?

The Correct Answer and Explanation is :

ER Diagram Design for a University Database System

Entities:

  1. Student
  • Attributes: Student_ID (PK), Name, Date_of_Birth, Email, Phone_Number, Major, Year_of_Enrollment
  1. Course
  • Attributes: Course_ID (PK), Course_Name, Credits, Department
  1. Professor
  • Attributes: Professor_ID (PK), Name, Email, Phone_Number, Department
  1. Department
  • Attributes: Department_ID (PK), Department_Name, Building
  1. Enrollment
  • Attributes: Enrollment_ID (PK), Grade, Student_ID (FK), Course_ID (FK)
  1. Teaching_Assignment
  • Attributes: Assignment_ID (PK), Professor_ID (FK), Course_ID (FK), Semester

Relationships:

  1. Student enrolls in Course
  • Relationship: Enrollment
  • Cardinality: A student can enroll in many courses, and each course can have many students.
  • This is a many-to-many relationship. We create an intermediate table/entity Enrollment to handle the relationship between Student and Course. This also includes the grade of the student for the course.
  1. Professor teaches Course
  • Relationship: Teaching_Assignment
  • Cardinality: A professor can teach many courses, but each course is taught by only one professor.
  • This is a many-to-one relationship from Teaching_Assignment to Professor and Course.
  1. Department offers Course
  • Relationship: Offers
  • Cardinality: A department can offer many courses, but a course is typically offered by only one department.
  • This is a one-to-many relationship from Department to Course.
  1. Professor belongs to Department
  • Relationship: Belongs_to
  • Cardinality: A professor belongs to one department, but a department can have many professors.
  • This is a many-to-one relationship from Professor to Department.

Design Explanation:

  1. Student-Course Relationship: The relationship between students and courses is essential to track which student is enrolled in which course. Since students can enroll in multiple courses and each course can have many students, we implement a many-to-many relationship using an Enrollment table, which stores the grade for each course taken by a student.
  2. Professor-Course Relationship: A professor teaches one or more courses, but each course is taught by one professor. Therefore, a many-to-one relationship exists between Teaching_Assignment and both Professor and Course.
  3. Department-Course and Department-Professor Relationships: Each department offers multiple courses and employs multiple professors. A department is therefore connected to both Course and Professor entities in one-to-many relationships.

This design efficiently tracks key relationships between students, professors, courses, and departments while maintaining clear cardinality constraints, which ensures the consistency of the data.

ER Diagram (Basic Overview):

[Student] ---<Enrollment>--- [Course] ---<Teaching_Assignment>--- [Professor] ---<Belongs_to>--- [Department]
   |                                                                       |
[Year_of_Enrollment]                                                     [Department_ID]

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