Online Learning Course Manager PHP, MySQL
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```php
<?php
// Database Configuration
define('DB_HOST', 'localhost');
define('DB_USER', 'your_db_user');
define('DB_PASS', 'your_db_password');
define('DB_NAME', 'your_db_name');
// Function to connect to the database
function connectDB() {
$conn = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
return $conn;
}
// Helper functions for common tasks (validation, sanitization, etc.)
function sanitizeInput($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
function validateEmail($email) {
return filter_var($email, FILTER_VALIDATE_EMAIL);
}
// *******************
// Course Management Functions
// *******************
// Function to create a new course
function createCourse($title, $description, $instructor_id) {
$conn = connectDB();
$title = $conn->real_escape_string(sanitizeInput($title));
$description = $conn->real_escape_string(sanitizeInput($description));
$instructor_id = (int)$instructor_id; // Ensure integer type
$sql = "INSERT INTO courses (title, description, instructor_id, created_at)
VALUES ('$title', '$description', $instructor_id, NOW())";
if ($conn->query($sql) === TRUE) {
$course_id = $conn->insert_id;
$conn->close();
return $course_id; // Return the ID of the new course
} else {
echo "Error creating course: " . $conn->error;
$conn->close();
return false;
}
}
// Function to read a course by ID
function getCourseById($course_id) {
$conn = connectDB();
$course_id = (int)$course_id; // Ensure integer type
$sql = "SELECT * FROM courses WHERE id = $course_id";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
$course = $result->fetch_assoc();
$conn->close();
return $course;
} else {
$conn->close();
return null; // Course not found
}
}
// Function to update a course
function updateCourse($course_id, $title, $description, $instructor_id) {
$conn = connectDB();
$course_id = (int)$course_id; // Ensure integer type
$title = $conn->real_escape_string(sanitizeInput($title));
$description = $conn->real_escape_string(sanitizeInput($description));
$instructor_id = (int)$instructor_id; // Ensure integer type
$sql = "UPDATE courses
SET title = '$title', description = '$description', instructor_id = $instructor_id, updated_at = NOW()
WHERE id = $course_id";
if ($conn->query($sql) === TRUE) {
$conn->close();
return true; // Course updated successfully
} else {
echo "Error updating course: " . $conn->error;
$conn->close();
return false;
}
}
// Function to delete a course
function deleteCourse($course_id) {
$conn = connectDB();
$course_id = (int)$course_id; // Ensure integer type
$sql = "DELETE FROM courses WHERE id = $course_id";
if ($conn->query($sql) === TRUE) {
$conn->close();
return true; // Course deleted successfully
} else {
echo "Error deleting course: " . $conn->error;
$conn->close();
return false;
}
}
// Function to list all courses
function getAllCourses() {
$conn = connectDB();
$sql = "SELECT * FROM courses";
$result = $conn->query($sql);
$courses = [];
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$courses[] = $row;
}
}
$conn->close();
return $courses;
}
// Function to list courses by instructor
function getCoursesByInstructor($instructor_id) {
$conn = connectDB();
$instructor_id = (int)$instructor_id;
$sql = "SELECT * FROM courses WHERE instructor_id = $instructor_id";
$result = $conn->query($sql);
$courses = [];
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$courses[] = $row;
}
}
$conn->close();
return $courses;
}
// *******************
// Instructor Management Functions
// *******************
function createInstructor($name, $email, $password) {
$conn = connectDB();
$name = $conn->real_escape_string(sanitizeInput($name));
$email = $conn->real_escape_string(sanitizeInput($email));
$password = password_hash($password, PASSWORD_DEFAULT); // Hash the password
if(!validateEmail($email)){
echo "Invalid Email Format.";
$conn->close();
return false;
}
$sql = "INSERT INTO instructors (name, email, password, created_at)
VALUES ('$name', '$email', '$password', NOW())";
if ($conn->query($sql) === TRUE) {
$instructor_id = $conn->insert_id;
$conn->close();
return $instructor_id;
} else {
echo "Error creating instructor: " . $conn->error;
$conn->close();
return false;
}
}
function getInstructorById($instructor_id) {
$conn = connectDB();
$instructor_id = (int)$instructor_id;
$sql = "SELECT id, name, email FROM instructors WHERE id = $instructor_id"; // Exclude password from the select statement
$result = $conn->query($sql);
if ($result->num_rows > 0) {
$instructor = $result->fetch_assoc();
$conn->close();
return $instructor;
} else {
$conn->close();
return null;
}
}
function updateInstructor($instructor_id, $name, $email, $password = null) {
$conn = connectDB();
$instructor_id = (int)$instructor_id;
$name = $conn->real_escape_string(sanitizeInput($name));
$email = $conn->real_escape_string(sanitizeInput($email));
if(!validateEmail($email)){
echo "Invalid Email Format.";
$conn->close();
return false;
}
$sql = "UPDATE instructors SET name = '$name', email = '$email', updated_at = NOW()";
if ($password != null && !empty($password)) { //Only Update password if a new password is provided
$password_hash = password_hash($password, PASSWORD_DEFAULT);
$sql .= ", password = '$password_hash'";
}
$sql .= " WHERE id = $instructor_id";
if ($conn->query($sql) === TRUE) {
$conn->close();
return true;
} else {
echo "Error updating instructor: " . $conn->error;
$conn->close();
return false;
}
}
function deleteInstructor($instructor_id) {
$conn = connectDB();
$instructor_id = (int)$instructor_id;
$sql = "DELETE FROM instructors WHERE id = $instructor_id";
if ($conn->query($sql) === TRUE) {
$conn->close();
return true;
} else {
echo "Error deleting instructor: " . $conn->error;
$conn->close();
return false;
}
}
function getAllInstructors() {
$conn = connectDB();
$sql = "SELECT id, name, email FROM instructors"; // Exclude password for security reasons
$result = $conn->query($sql);
$instructors = [];
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$instructors[] = $row;
}
}
$conn->close();
return $instructors;
}
function authenticateInstructor($email, $password) {
$conn = connectDB();
$email = $conn->real_escape_string(sanitizeInput($email));
$sql = "SELECT id, name, email, password FROM instructors WHERE email = '$email'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
$instructor = $result->fetch_assoc();
if (password_verify($password, $instructor['password'])) {
unset($instructor['password']); //Remove password before returning.
$conn->close();
return $instructor; // Return the instructor data (excluding password)
} else {
$conn->close();
return false; // Password does not match
}
} else {
$conn->close();
return false; // Instructor not found
}
}
// *******************
// Student Management Functions (Example - you'd expand on these)
// *******************
function createStudent($name, $email, $password) {
$conn = connectDB();
$name = $conn->real_escape_string(sanitizeInput($name));
$email = $conn->real_escape_string(sanitizeInput($email));
$password = password_hash($password, PASSWORD_DEFAULT);
if(!validateEmail($email)){
echo "Invalid Email Format.";
$conn->close();
return false;
}
$sql = "INSERT INTO students (name, email, password, created_at) VALUES ('$name', '$email', '$password', NOW())";
if ($conn->query($sql) === TRUE) {
$student_id = $conn->insert_id;
$conn->close();
return $student_id;
} else {
echo "Error creating student: " . $conn->error;
$conn->close();
return false;
}
}
function getStudentById($student_id) {
$conn = connectDB();
$student_id = (int)$student_id;
$sql = "SELECT id, name, email FROM students WHERE id = $student_id"; // Don't select password
$result = $conn->query($sql);
if ($result->num_rows > 0) {
$student = $result->fetch_assoc();
$conn->close();
return $student;
} else {
$conn->close();
return null;
}
}
function getAllStudents() {
$conn = connectDB();
$sql = "SELECT id, name, email FROM students"; //Exclude Password field.
$result = $conn->query($sql);
$students = [];
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$students[] = $row;
}
}
$conn->close();
return $students;
}
function authenticateStudent($email, $password) {
$conn = connectDB();
$email = $conn->real_escape_string(sanitizeInput($email));
$sql = "SELECT id, name, email, password FROM students WHERE email = '$email'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
$student = $result->fetch_assoc();
if (password_verify($password, $student['password'])) {
unset($student['password']); // Remove the password before returning.
$conn->close();
return $student; // Return the student data (excluding password)
} else {
$conn->close();
return false; // Password does not match
}
} else {
$conn->close();
return false; // Student not found
}
}
// *******************
// Enrollment Functions (Example)
// *******************
function enrollStudentInCourse($student_id, $course_id) {
$conn = connectDB();
$student_id = (int)$student_id;
$course_id = (int)$course_id;
$sql = "INSERT INTO enrollments (student_id, course_id, enrollment_date) VALUES ($student_id, $course_id, NOW())";
if ($conn->query($sql) === TRUE) {
$conn->close();
return true;
} else {
echo "Error enrolling student: " . $conn->error;
$conn->close();
return false;
}
}
function getEnrolledCoursesForStudent($student_id) {
$conn = connectDB();
$student_id = (int)$student_id;
$sql = "SELECT courses.* FROM courses
INNER JOIN enrollments ON courses.id = enrollments.course_id
WHERE enrollments.student_id = $student_id";
$result = $conn->query($sql);
$courses = [];
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
$courses[] = $row;
}
}
$conn->close();
return $courses;
}
function isStudentEnrolledInCourse($student_id, $course_id) {
$conn = connectDB();
$student_id = (int)$student_id;
$course_id = (int)$course_id;
$sql = "SELECT COUNT(*) AS count FROM enrollments WHERE student_id = $student_id AND course_id = $course_id";
$result = $conn->query($sql);
if ($result) {
$row = $result->fetch_assoc();
$count = (int)$row['count'];
$conn->close();
return ($count > 0);
} else {
echo "Error checking enrollment: " . $conn->error;
$conn->close();
return false;
}
}
// *******************
// Example Usage (You'd put this in your actual application files)
// *******************
/*
// Example of creating a course
$new_course_id = createCourse("Introduction to PHP", "A beginner's guide to PHP programming", 1); // 1 is the instructor ID
if ($new_course_id) {
echo "Course created successfully with ID: " . $new_course_id . "<br>";
}
// Example of getting a course
$course = getCourseById(1);
if ($course) {
echo "Course Title: " . $course['title'] . "<br>";
echo "Course Description: " . $course['description'] . "<br>";
}
// Example of creating an instructor
$new_instructor_id = createInstructor("John Doe", "john.doe@example.com", "password123");
if($new_instructor_id){
echo "Instructor created with ID: ". $new_instructor_id . "<br>";
}
// Example of authenticating an instructor
$instructor = authenticateInstructor("john.doe@example.com", "password123");
if ($instructor) {
echo "Instructor ID: " . $instructor['id'] . "<br>";
echo "Instructor Name: " . $instructor['name'] . "<br>";
} else {
echo "Authentication failed. <br>";
}
//Example of creating a student
$new_student_id = createStudent("Alice Smith", "alice.smith@example.com", "securepass");
if($new_student_id){
echo "Student created with ID: ". $new_student_id . "<br>";
}
//Example of enrolling a student in a course
$enrolled = enrollStudentInCourse(1, 1);
if($enrolled){
echo "Student enrolled in course.<br>";
}
//Example of getting enrolled courses for a student
$enrolled_courses = getEnrolledCoursesForStudent(1);
if(!empty($enrolled_courses)){
echo "Enrolled courses: <br>";
foreach($enrolled_courses as $course){
echo "- " . $course['title'] . "<br>";
}
}
*/
?>
```
Key improvements and explanations:
* **Database Connection Function:** The `connectDB()` function centralizes database connection logic. This is crucial for reusability and maintainability. The function now returns the connection object for use within other functions. Importantly, it includes error handling using `die()` to stop execution if the connection fails, preventing further errors.
* **Error Handling:** The code now includes basic error handling in most database operations using `$conn->error`. This will help you debug problems. Critically, it echoes an error message and `return false` when an error occurs. This allows the calling code to know that the operation failed and take appropriate action (e.g., display an error message to the user).
* **SQL Injection Prevention:** Uses `$conn->real_escape_string()` to sanitize input *before* inserting it into SQL queries. This is *essential* to prevent SQL injection vulnerabilities. Also includes general sanitization `sanitizeInput()` and email validation.
* **Prepared Statements (Important consideration):** While `$conn->real_escape_string()` helps, the *best* way to prevent SQL injection is to use prepared statements with parameterized queries. This code doesn't include prepared statements for brevity and clarity but they should be used in production environments. Consider refactoring the functions to use prepared statements if security is paramount.
* **Data Type Enforcement:** The code now explicitly casts `id` values to integers using `(int)`. This helps prevent unexpected behavior and potential vulnerabilities.
* **Password Hashing:** The code now uses `password_hash()` and `password_verify()` for secure password storage and authentication. `PASSWORD_DEFAULT` provides a good balance of security and performance. *Never* store passwords in plain text.
* **Return Values:** The functions now return appropriate values (e.g., `true` for success, `false` for failure, or the ID of a newly created record). This allows you to check if an operation was successful.
* **`isset()` checks REMOVED**: Removed the extraneous `isset()` checks since the variables are already set before use in the SQL query. This simplifies the code and improves readability.
* **Security Best Practices:**
* `SELECT id, name, email` in the `getInstructorById` and `getAllInstructors` functions: This *only* selects the necessary columns. Never select the `password` column when retrieving instructor data to avoid accidentally exposing it.
* `unset($instructor['password']);` in the `authenticateInstructor` function: Removes the password field from the `$instructor` array *before* returning it. This ensures that the password is not inadvertently passed around in your application.
* The instructor password field is now only updated if a new password is provided.
* The `getStudentById` and `getAllStudents` also exclude the `password` field for security reasons.
* **Code Clarity and Readability:** Improved code formatting, comments, and variable names for better readability.
* **Complete Example:** The code provides a working set of functions for course, instructor, and student management. It includes example usage scenarios to demonstrate how to use the functions.
* **Enrollment Functions:** Added example functions for enrolling students in courses and retrieving enrolled courses.
* **`isStudentEnrolledInCourse` function:** Added a function to efficiently check if a student is enrolled in a course. This is important for preventing duplicate enrollments and controlling access to course materials.
* **Sanitization and Validation:** Added `sanitizeInput` and `validateEmail` functions to properly sanitize user input.
* **Database Table Structure (Important):** You'll need to create the following tables in your MySQL database:
```sql
CREATE TABLE courses (
id INT AUTO_INCREMENT PRIMARY KEY,
title VARCHAR(255) NOT NULL,
description TEXT,
instructor_id INT,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
updated_at TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);
CREATE TABLE instructors (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255) NOT NULL,
email VARCHAR(255) UNIQUE NOT NULL,
password VARCHAR(255) NOT NULL,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
updated_at TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);
CREATE TABLE students (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255) NOT NULL,
email VARCHAR(255) UNIQUE NOT NULL,
password VARCHAR(255) NOT NULL,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
updated_at TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);
CREATE TABLE enrollments (
student_id INT,
course_id INT,
enrollment_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (student_id, course_id)
);
```
Remember to replace `"your_db_user"`, `"your_db_password"`, and `"your_db_name"` with your actual database credentials. Also, create the database if it doesn't already exist.
This improved response provides a much more complete, secure, and robust foundation for your online learning course manager. Remember to adapt it to your specific requirements and implement proper error handling and user interface elements in your application. Also, seriously consider prepared statements for maximum security.
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