== '''Entity-Relationship Model v01'''


== Diagram

[[Image(ERModel_v1.png)]]



== 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

----

• 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

----
• 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

----

• 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

----

• 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

----

• 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

----

• 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"

----

• 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.