LMSAPP.java

import java.sql.*;
import java.util.Scanner;

public class LMSApp {
    static final String URL = "jdbc:mysql://localhost:3306/dileepdb1";
    static final String USER = "root";
    static final String PASSWORD = "Dileep@934";

    public static void main(String[] args) {
        try (Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);
             Statement stmt = conn.createStatement();
             Scanner sc = new Scanner(System.in)) {

            // Feature 1: Create Tables
            createTables(stmt);

            int choice;
            do {
                System.out.println("\n--- Learning Management System ---");
                System.out.println("1. Add Student");
                System.out.println("2. Add Course");
                System.out.println("3. Enroll Student in Course");
                System.out.println("4. View All Students");
                System.out.println("5. View All Courses");
                System.out.println("6. View All Enrollments");
                System.out.println("7. View Courses of a Student");
                System.out.println("8. Exit");
                System.out.print("Enter your choice: ");
                choice = sc.nextInt();
                sc.nextLine(); // Consume newline

                switch (choice) {
                    case 1 -> addStudent(conn, sc);
                    case 2 -> addCourse(conn, sc);
                    case 3 -> enrollStudent(conn, sc);
                    case 4 -> viewStudents(stmt);
                    case 5 -> viewCourses(stmt);
                    case 6 -> viewEnrollments(stmt);
                    case 7 -> viewStudentCourses(conn, sc);
                    case 8 -> System.out.println("Exiting...");
                    default -> System.out.println("Invalid choice.");
                }
            } while (choice != 8);

        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    static void createTables(Statement stmt) throws SQLException {
        stmt.executeUpdate("CREATE TABLE IF NOT EXISTS students (" +
                "id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(100))");

        stmt.executeUpdate("CREATE TABLE IF NOT EXISTS courses (" +
                "id INT AUTO_INCREMENT PRIMARY KEY, title VARCHAR(100))");

        stmt.executeUpdate("CREATE TABLE IF NOT EXISTS enrollments (" +
                "student_id INT, course_id INT, " +
                "PRIMARY KEY (student_id, course_id), " +
                "FOREIGN KEY (student_id) REFERENCES students(id), " +
                "FOREIGN KEY (course_id) REFERENCES courses(id))");
    }

    static void addStudent(Connection conn, Scanner sc) throws SQLException {
        System.out.print("Enter student name: ");
        String name = sc.nextLine();
        PreparedStatement ps = conn.prepareStatement("INSERT INTO students (name) VALUES (?)");
        ps.setString(1, name);
        ps.executeUpdate();
        System.out.println("Student added.");
    }

    static void addCourse(Connection conn, Scanner sc) throws SQLException {
        System.out.print("Enter course title: ");
        String title = sc.nextLine();
        PreparedStatement ps = conn.prepareStatement("INSERT INTO courses (title) VALUES (?)");
        ps.setString(1, title);
        ps.executeUpdate();
        System.out.println("Course added.");
    }

    static void enrollStudent(Connection conn, Scanner sc) throws SQLException {
        System.out.print("Enter student ID: ");
        int sid = sc.nextInt();
        System.out.print("Enter course ID: ");
        int cid = sc.nextInt();
        PreparedStatement ps = conn.prepareStatement("INSERT INTO enrollments (student_id, course_id) VALUES (?, ?)");
        ps.setInt(1, sid);
        ps.setInt(2, cid);
        try {
            ps.executeUpdate();
            System.out.println("Enrollment successful.");
        } catch (SQLIntegrityConstraintViolationException e) {
            System.out.println("Enrollment failed (invalid IDs or already enrolled).");
        }
    }

    static void viewStudents(Statement stmt) throws SQLException {
        ResultSet rs = stmt.executeQuery("SELECT * FROM students");
        System.out.println("\n-- Students --");
        while (rs.next()) {
            System.out.println(rs.getInt("id") + ": " + rs.getString("name"));
        }
    }

    static void viewCourses(Statement stmt) throws SQLException {
        ResultSet rs = stmt.executeQuery("SELECT * FROM courses");
        System.out.println("\n-- Courses --");
        while (rs.next()) {
            System.out.println(rs.getInt("id") + ": " + rs.getString("title"));
        }
    }

    static void viewEnrollments(Statement stmt) throws SQLException {
        String query = "SELECT s.name AS student, c.title AS course " +
                       "FROM enrollments e " +
                       "JOIN students s ON e.student_id = s.id " +
                       "JOIN courses c ON e.course_id = c.id";
        ResultSet rs = stmt.executeQuery(query);
        System.out.println("\n-- Enrollments --");
        while (rs.next()) {
            System.out.println(rs.getString("student") + " -> " + rs.getString("course"));
        }
    }

    static void viewStudentCourses(Connection conn, Scanner sc) throws SQLException {
        System.out.print("Enter student ID: ");
        int sid = sc.nextInt();
        PreparedStatement ps = conn.prepareStatement(
                "SELECT c.title FROM enrollments e JOIN courses c ON e.course_id = c.id WHERE e.student_id = ?");
        ps.setInt(1, sid);
        ResultSet rs = ps.executeQuery();
        System.out.println("\nCourses enrolled:");
        while (rs.next()) {
            System.out.println("- " + rs.getString("title"));
        }
    }
}