Entity-Relationship Model v01

Diagram

Data Requirements

• University: This entity stores information about universities. We need it to know which faculties belong to which university.

º Candidate keys: Id (primary key).

º Attributes:

Id – number, required, unique

Name – text, required, max 255 characters

Location – text, optional, max 255 characters

isprivate – boolean, required

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• Faculty: Represents a faculty inside a university. It helps organize students, professors, and subjects within that faculty. Each faculty belongs to one university.

º Candidate keys: Id (primary key).

º Attributes:

Id – number, required, unique

Name – text, required, max 255 characters

Location – text, optional, max 255 characters

Study_field – text, optional, max 255 characters

University_Id – number, required, foreign key to University

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• Professor: This entity stores professors. Each professor works in a specific faculty, can guide students through advice sessions, and is assigned to teach subjects inside student enrollments.

º Candidate keys: Id (primary key).

º Attributes:

Id – number, required, unique

Name – text, required, max 255 characters

Surname – text, optional, max 255 characters

Age – number, optional, 25–100

Faculty_Id – number, required, foreign key to Faculty

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• Student: This entity stores students. Each student belongs to a faculty, can enroll in subjects, and can interact with professors during advice sessions.

º Candidate keys: Id (primary key).

º Attributes:

Id – number, required, unique

Name – text, required, max 255 characters

Surname – text, optional, max 255 characters

Location – text, optional, max 255 characters

Index – number, required, unique

Faculty_Id – number, required, foreign key to Faculty

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• Subject: This entity stores courses or subjects offered by a faculty. Students can enroll in these subjects.

º Candidate keys: Id (primary key).

º Attributes:

Id – number, required, unique

Name – text, required, max 255 characters

Semester – text, optional, e.g., "Fall", "Spring"

Credits – number, required, 1–15

Faculty_Id – number, required, foreign key to Faculty

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• Student_Subject: This entity represents a specific student enrollment in a subject. It tracks grades, attendance, and status. It also links the specific professor who teaches this instance of the course.

º Candidate keys: ssId (primary key).

º Attributes:

ssId – number, required, unique

Final_Grade – number, optional, 6–10

Status – text, optional, e.g., "Enrolled", "Passed", "Failed"

Enrollment_Date – date, required

Absence_Count – number, optional, 0–100

Student_Id – number, required, foreign key to Student

Subject_Id – number, required, foreign key to Subject

Professor_Id – number, required, foreign key to Professor

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• Advice: This ternary associative relationship entity tracks the history of formal advice and mentorship sessions between professors and students.

º Candidate keys: Composite key made of (student_id, professor_id, start_date).

º Attributes:

student_id – number, required, foreign key to Student

professor_id – number, required, foreign key to Professor

start_date – date, required, unique part of the key

end_date – date, optional

status – text, optional, e.g., "Active", "Completed"

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• Professor_Subject: This bridge entity materializes the Many-to-Many relationship between professors and the subjects they are certified or eligible to teach.

º Candidate keys: Composite key made of (subject_id, professor_id).

º Attributes:

subject_id – number, required, foreign key to Subject

professor_id – number, required, foreign key to Professor

Entity-Relationship Model History

v1: First version of the conceptual ER model including University, Faculty, Professor, Student, Subject, Student_Subject weak entity, advice mentorship tracking, and professor_subject competency mapping. Attributes, candidate keys, nullability constraints, and precise entity relationships defined.