public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

Connection connection = null;

try {

connection = MyJDBCConnection.getConnection();

while (true) {

System.out.println("Enter the Option:\n (1) View All Students \n (2) Add new Student");

int option = scanner.nextInt();

switch(option){

case 1:

printAllStudents(connection);

break;

case 2:

System.out.print("Enter Student ID: ");

int studentId = scanner.nextInt();

scanner.nextLine();

String existingStudentName = getStudentNameById(connection, studentId);

if (existingStudentName != null) {

System.out.println("ERROR: Student ID (" + studentId + ") you entered is belongs to (" + existingStudentName +

") please enter a unique ID");

continue;

}

System.out.print("Enter First Name: ");

String firstName = scanner.nextLine();

System.out.print("Enter Last Name: ");

String lastName = scanner.nextLine();

System.out.print("Enter Age: ");

int age = scanner.nextInt();

scanner.nextLine(); // Consume newline

System.out.print("Enter Grade: ");

String grade = scanner.nextLine();

insertStudent(connection, studentId, firstName, lastName, age, grade);

System.out.println("Student Details Stored Successfully");

break;

}

}

} catch (SQLException e) {

e.printStackTrace();

} finally {

try {

if (connection != null) connection.close();

scanner.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

}

private static void printAllStudents(Connection connection) throws SQLException {

String query = "SELECT * FROM student_details";

try (PreparedStatement pstmt = connection.prepareStatement(query);

ResultSet rs = pstmt.executeQuery()) {

System.out.println("\n--- Student Details ---");

System.out.printf("%-10s %-15s %-15s %-5s %-10s%n", "ID", "First Name", "Last Name", "Age", "Grade");

System.out.println("------------------------------------------------------");

while (rs.next()) {

int studentId = rs.getInt("student_id");

String firstName = rs.getString("first_name");

String lastName = rs.getString("last_name");

int age = rs.getInt("age");

String grade = rs.getString("grade");

System.out.printf("%-10d %-15s %-15s %-5d %-10s%n", studentId, firstName, lastName, age, grade);

}

}

}

private static String getStudentNameById(Connection connection, int studentId) throws SQLException {

String query = "SELECT first_name FROM student_details WHERE student_id = ?";

try (PreparedStatement pstmt = connection.prepareStatement(query)) {

pstmt.setInt(1, studentId);

ResultSet rs = pstmt.executeQuery();

if (rs.next()) {

return rs.getString("first_name");

}

}

return null;

}

private static void insertStudent(Connection connection, int studentId, String firstName, String lastName, int age, String grade) throws SQLException{

String insertQuery = "INSERT INTO student_details (student_id, first_name, last_name, age, grade) VALUES (?,?,?,?,?)";

try(PreparedStatement pstmt = connection.prepareStatement(insertQuery)){

pstmt.setInt(1,studentId);

pstmt.setString(2,firstName);

pstmt.setString(3,lastName);

pstmt.setInt(4,age);

pstmt.setString(5,grade);

pstmt.executeUpdate();

}

}