Enrollment Management

Overview

The Enrollment Management system allows administrators to register students in courses, manage course rosters, and prevent duplicate enrollments. Enrollments create the link between students and courses, enabling grade tracking and timetable access.

Student Enrollment

Enrollment Listing

View all active enrollments with student and course details

Duplicate Prevention

Automatic detection of duplicate enrollments

Enrollment Deletion

Remove students from courses

What is an Enrollment?

An enrollment represents a student’s registration in a specific course. For example:

“John Doe enrolled in Mathematics (taught by Mr. Smith)”
“Jane Smith enrolled in Physics (taught by Dr. Johnson)”

Enrollment Components:

Student: The enrolled student
Course: The specific course instance (subject + teacher)
Composite Key: Combination of student_id and course_id must be unique

Database Schema

CREATE TABLE enrollments (
    student_id INT NOT NULL,
    course_id INT NOT NULL,
    PRIMARY KEY (student_id, course_id),
    FOREIGN KEY (student_id) REFERENCES students(id) ON DELETE CASCADE,
    FOREIGN KEY (course_id) REFERENCES courses(id) ON DELETE CASCADE
);

Schema Design Explanation

Composite Primary Key:

Uses both student_id and course_id as primary key
Automatically prevents duplicate enrollments at database level
A student can only be enrolled once in any given course

Cascade Deletion:

If student is deleted, all their enrollments are removed
If course is deleted, all enrollments in that course are removed
Maintains data integrity automatically

Enrollment Operations

Viewing All Enrollments

Administrators can view complete enrollment roster:

// EnrollmentController.php - index()
public function index()
{
    Auth::admin(); // Only admins can view all enrollments

    $enrollments = $this->enrollmentModel->getAll();
    require __DIR__ . '/../views/enrollments/index.php';
}

// Enrollment.php - getAll()
public function getAll()
{
    $sql = "SELECT 
                students.id AS student_id,
                users.name AS student_name,
                subjects.name AS subject_name,
                courses.id AS course_id
            FROM enrollments
            JOIN students ON enrollments.student_id = students.id
            JOIN users ON students.id = users.id
            JOIN courses ON enrollments.course_id = courses.id
            JOIN subjects ON courses.subject_id = subjects.id";

    return $this->db->query($sql)->fetchAll(PDO::FETCH_ASSOC);
}

Query Breakdown

This complex query joins multiple tables:

enrollments → students: Get student information
students → users: Get student name and details
enrollments → courses: Get course information
courses → subjects: Get subject name

Result includes:

Student ID and name
Course ID and subject name
All data needed for enrollment management

Creating Enrollments

Enrollment creation with duplicate prevention:

// EnrollmentController.php - create() and store()
public function create()
{
    Auth::admin();

    // Load students and courses for selection
    $students = $this->studentModel->getAll();
    $courses = $this->courseModel->getAll();

    require __DIR__ . '/../views/enrollments/create.php';
}

public function store()
{
    Auth::admin();

    $student_id = $_POST['student_id'];
    $course_id = $_POST['course_id'];

    // Check if already enrolled
    if ($this->enrollmentModel->isAlreadyEnrolled($student_id, $course_id)) {
        header("Location: /enrollments/create?error=duplicate");
        exit;
    }

    // Create enrollment
    $this->enrollmentModel->create($student_id, $course_id);

    header("Location: /enrollments");
    exit;
}

// Enrollment.php - create()
public function create($student_id, $course_id)
{
    $stmt = $this->db->prepare(
        "INSERT INTO enrollments (student_id, course_id) VALUES (?, ?)"
    );
    return $stmt->execute([$student_id, $course_id]);
}

Enrollment Workflow:

Admin selects student from dropdown
Admin selects course from dropdown
System checks for duplicate enrollment
If duplicate, redirect with error message
If unique, create enrollment record
Student can now access course in their timetable and receive grades

Duplicate Detection

Prevents students from being enrolled multiple times in the same course:

// Enrollment.php - isAlreadyEnrolled()
public function isAlreadyEnrolled($student_id, $course_id)
{
    $stmt = $this->db->prepare(
        "SELECT COUNT(*) FROM enrollments 
         WHERE student_id = ? AND course_id = ?"
    );
    $stmt->execute([$student_id, $course_id]);
    return $stmt->fetchColumn() > 0;
}

Usage pattern:

// Check before inserting
if ($this->enrollmentModel->isAlreadyEnrolled($student_id, $course_id)) {
    // Redirect with error
    header("Location: /enrollments/create?error=duplicate");
    exit;
}

// Safe to insert
$this->enrollmentModel->create($student_id, $course_id);

Why Check Duplicates?

Provides user-friendly error messages
Allows controlled handling of duplicate attempts
Database composite key also prevents duplicates, but checking first gives better UX

Deleting Enrollments

Remove a student from a course:

// EnrollmentController.php - delete()
public function delete()
{
    Auth::admin();

    $this->enrollmentModel->delete(
        $_GET['student_id'],
        $_GET['course_id']
    );

    header("Location: /enrollments");
    exit;
}

// Enrollment.php - delete()
public function delete($student_id, $course_id)
{
    $stmt = $this->db->prepare(
        "DELETE FROM enrollments 
         WHERE student_id=? AND course_id=?"
    );
    $stmt->execute([$student_id, $course_id]);
}

Deletion Effects:

Student loses access to course in timetable
Grades for this course remain in database (not deleted)
Can be re-enrolled later if needed

Student-Specific Queries

Getting Student’s Enrollments

Retrieve all courses a student is enrolled in:

// Enrollment.php - getByStudent()
public function getByStudent($student_id)
{
    $stmt = $this->db->prepare("
        SELECT enrollments.*
        FROM enrollments
        WHERE enrollments.student_id = ?
    ");
    $stmt->execute([$student_id]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

This is used in:

Timetable Generation: Show only enrolled courses in student’s schedule
Grade Display: Show grades only for enrolled courses
Bulletin Generation: Calculate averages from enrolled courses

Integration with Other Systems

Grade Entry (Teacher Perspective)

Teachers can only enter grades for enrolled students:

// Grade.php - getStudentsByCourse()
public function getStudentsByCourse($course_id)
{
    $stmt = $this->db->prepare("
        SELECT students.id, users.name, grades.grade
        FROM enrollments
        JOIN students ON enrollments.student_id = students.id
        JOIN users ON students.id = users.id
        LEFT JOIN grades 
          ON grades.student_id = students.id 
         AND grades.course_id = enrollments.course_id
        WHERE enrollments.course_id = ?
    ");
    $stmt->execute([$course_id]);
    return $stmt->fetchAll();
}

Query Explanation

This query:

Starts with enrollments for the course
Joins to get student information
LEFT JOINs grades (may not exist yet)
Shows all enrolled students with their current grade (or NULL)

Purpose:

Teachers see complete enrollment roster
Existing grades are displayed
Students without grades show NULL (can add grade)
Only enrolled students appear in the list

Timetable Access (Student Perspective)

Students only see timetable entries for enrolled courses:

// Timetable.php - getForStudent()
public function getForStudent($student_id)
{
    $sql = "
        SELECT 
            subjects.name AS subject,
            users.name AS teacher,
            timetable.day,
            timetable.start_time,
            timetable.end_time
        FROM timetable
        JOIN courses ON courses.id = timetable.course_id
        JOIN enrollments ON enrollments.course_id = courses.id
        JOIN subjects ON subjects.id = courses.subject_id
        JOIN teachers ON teachers.id = courses.teacher_id
        JOIN users ON users.id = teachers.id
        WHERE enrollments.student_id = ?
        ORDER BY timetable.day, timetable.start_time
    ";

    $stmt = $this->db->prepare($sql);
    $stmt->execute([$student_id]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

Key point: JOIN enrollments filters timetable to only enrolled courses.

Bulletin Generation

Bulletins include grades from all enrolled courses:

// Grade.php - getBulletinData()
public function getBulletinData($student_id)
{
    $sql = "
        SELECT 
            subjects.name AS subject,
            users.name AS teacher,
            grades.grade
        FROM grades
        JOIN courses ON grades.course_id = courses.id
        JOIN subjects ON courses.subject_id = subjects.id
        JOIN users ON courses.teacher_id = users.id
        WHERE grades.student_id = ?
    ";

    $stmt = $this->db->prepare($sql);
    $stmt->execute([$student_id]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

Note: This query uses grades table, not enrollments. Students may be enrolled in courses without grades yet. Bulletin only shows courses with recorded grades.

Complete Enrollment Model

// Enrollment.php - Full implementation
class Enrollment
{
    private $db;

    public function __construct()
    {
        $this->db = Database::getInstance()->getConnection();
    }

    // Get all enrollments with details
    public function getAll()
    {
        $sql = "SELECT 
                    students.id AS student_id,
                    users.name AS student_name,
                    subjects.name AS subject_name,
                    courses.id AS course_id
                FROM enrollments
                JOIN students ON enrollments.student_id = students.id
                JOIN users ON students.id = users.id
                JOIN courses ON enrollments.course_id = courses.id
                JOIN subjects ON courses.subject_id = subjects.id";

        return $this->db->query($sql)->fetchAll(PDO::FETCH_ASSOC);
    }

    // Create new enrollment
    public function create($student_id, $course_id)
    {
        $stmt = $this->db->prepare(
            "INSERT INTO enrollments (student_id, course_id) VALUES (?, ?)"
        );
        return $stmt->execute([$student_id, $course_id]);
    }

    // Delete enrollment
    public function delete($student_id, $course_id)
    {
        $stmt = $this->db->prepare(
            "DELETE FROM enrollments WHERE student_id=? AND course_id=?"
        );
        $stmt->execute([$student_id, $course_id]);
    }

    // Get enrollments for specific student
    public function getByStudent($student_id)
    {
        $stmt = $this->db->prepare("
            SELECT enrollments.*
            FROM enrollments
            WHERE enrollments.student_id = ?
        ");
        $stmt->execute([$student_id]);
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    // Check if student already enrolled in course
    public function isAlreadyEnrolled($student_id, $course_id)
    {
        $stmt = $this->db->prepare(
            "SELECT COUNT(*) FROM enrollments 
             WHERE student_id = ? AND course_id = ?"
        );
        $stmt->execute([$student_id, $course_id]);
        return $stmt->fetchColumn() > 0;
    }
}

API Endpoints

Method	Endpoint	Access	Description
GET	`/enrollments`	Admin	List all enrollments
GET	`/enrollments/create`	Admin	Show enrollment form
POST	`/enrollments/store`	Admin	Create new enrollment
GET	`/enrollments/delete?student_id={sid}&course_id={cid}`	Admin	Delete enrollment

Use Cases

Scenario 1: Enrolling a New Student

Context: John Doe needs to be enrolled in MathematicsSteps:

Admin navigates to /enrollments/create
Selects “John Doe” from students dropdown
Selects “Mathematics - Mr. Smith” from courses dropdown
Submits form
System checks: isAlreadyEnrolled(john_id, math_course_id)
If not enrolled, creates enrollment record
John can now see Mathematics in his timetable
Mr. Smith can enter grades for John in Mathematics

Scenario 2: Duplicate Enrollment Attempt

Context: Admin tries to enroll John in Mathematics againSteps:

Admin selects “John Doe” and “Mathematics - Mr. Smith”
Submits enrollment form
System checks: isAlreadyEnrolled(john_id, math_course_id) → true
Redirects to /enrollments/create?error=duplicate
Shows error message: “Student already enrolled”
No duplicate enrollment created

Scenario 3: Removing Student from Course

Context: Jane Smith needs to drop PhysicsSteps:

Admin views enrollment list
Finds “Jane Smith - Physics”
Clicks delete button
System calls delete(jane_id, physics_course_id)
Enrollment record removed
Jane no longer sees Physics in her timetable
Physics teacher no longer sees Jane in course roster
Jane’s Physics grades remain in database (historical record)

Data Flow Diagram

┌──────────┐
│ Students │
└────┬─────┘
     │
     │ student_id
     ▼
┌──────────────┐      course_id      ┌──────────┐
│ Enrollments  │◄────────────────────│ Courses  │
│──────────────│                     └────┬─────┘
│ student_id   │                          │
│ course_id    │                          │
└──────┬───────┘                          │
       │                                  │
       └──────────┬───────────────────────┘
                  │
         Used by: │
                  ├─► Timetable (filter student schedule)
                  ├─► Grades (determine course roster)
                  └─► Bulletin (list enrolled courses)

Central Role of Enrollments: Enrollments are the bridge between students and courses. Without enrollment:

Students don’t appear in course rosters
Teachers can’t enter grades
Students don’t see courses in timetable
Courses don’t appear in student bulletins

Best Practices

Validation

Always check for duplicate enrollments
Verify student and course exist before creating
Use composite primary key for database-level enforcement

User Experience

Provide clear error messages for duplicates
Show course and student names in listings
Confirm before deleting enrollments

Data Integrity

Use foreign key constraints
Enable cascade deletion
Keep historical grade data even after unenrollment

Security

Restrict enrollment operations to admins only
Validate all input data
Use prepared statements for all queries

Getting Started

User Guides

Core Features

Architecture

Overview

Student Enrollment

Enrollment Listing

Duplicate Prevention

Enrollment Deletion

What is an Enrollment?

Database Schema

Enrollment Operations

Viewing All Enrollments

Creating Enrollments

Duplicate Detection

Deleting Enrollments

Student-Specific Queries

Getting Student’s Enrollments

Integration with Other Systems

Grade Entry (Teacher Perspective)

Timetable Access (Student Perspective)

Bulletin Generation

Complete Enrollment Model

API Endpoints

Use Cases

Data Flow Diagram

Best Practices

Validation

User Experience

Data Integrity

Security

Build docs developers (and LLMs) love

Getting Started

User Guides

Core Features

Architecture

​Overview

Student Enrollment

Enrollment Listing

Duplicate Prevention

Enrollment Deletion

​What is an Enrollment?

​Database Schema

​Enrollment Operations

​Viewing All Enrollments

​Creating Enrollments

​Duplicate Detection

​Deleting Enrollments

​Student-Specific Queries

​Getting Student’s Enrollments

​Integration with Other Systems

​Grade Entry (Teacher Perspective)

​Timetable Access (Student Perspective)

​Bulletin Generation

​Complete Enrollment Model

​API Endpoints

​Use Cases

​Data Flow Diagram

​Best Practices

Validation

User Experience

Data Integrity

Security

Build docs developers (and LLMs) love

Overview

What is an Enrollment?

Database Schema

Enrollment Operations

Viewing All Enrollments

Creating Enrollments

Duplicate Detection

Deleting Enrollments

Student-Specific Queries

Getting Student’s Enrollments

Integration with Other Systems

Grade Entry (Teacher Perspective)

Timetable Access (Student Perspective)

Bulletin Generation

Complete Enrollment Model

API Endpoints

Use Cases

Data Flow Diagram

Best Practices