Bagaimana untuk membangunkan sistem pengurusan kakitangan yang mudah menggunakan MySQL dan Java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/hrms";
    private static final String USER = "root";
    private static final String PASSWORD = "password";

    public static Connection getConnection() {
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USER, PASSWORD);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class EmployeeDao {
    public static void addEmployee(Employee employee) {
        Connection conn = DBUtil.getConnection();
        String sql = "INSERT INTO employee (id, name, gender, birthday, hire_date) VALUES (?,?,?,?,?)";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setInt(1, employee.getId());
            pstmt.setString(2, employee.getName());
            pstmt.setString(3, employee.getGender());
            pstmt.setString(4, employee.getBirthday());
            pstmt.setString(5, employee.getHireDate());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void updateEmployee(Employee employee) {
        Connection conn = DBUtil.getConnection();
        String sql = "UPDATE employee SET name=?, gender=?, birthday=?, hire_date=? WHERE id=?";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setString(1, employee.getName());
            pstmt.setString(2, employee.getGender());
            pstmt.setString(3, employee.getBirthday());
            pstmt.setString(4, employee.getHireDate());
            pstmt.setInt(5, employee.getId());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void deleteEmployee(int id) {
        Connection conn = DBUtil.getConnection();
        String sql = "DELETE FROM employee WHERE id=?";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static Employee getEmployeeById(int id) {
        Connection conn = DBUtil.getConnection();
        String sql = "SELECT * FROM employee WHERE id=?";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                Employee employee = new Employee();
                employee.setId(rs.getInt("id"));
                employee.setName(rs.getString("name"));
                employee.setGender(rs.getString("gender"));
                employee.setBirthday(rs.getString("birthday"));
                employee.setHireDate(rs.getString("hire_date"));
                return employee;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
}

public class Test {
    public static void main(String[] args) {
        Employee employee = new Employee();
        employee.setId(1);
        employee.setName("张三");
        employee.setGender("男");
        employee.setBirthday("1990-01-01");
        employee.setHireDate("2020-01-01");

        EmployeeDao.addEmployee(employee);

        Employee updatedEmployee = new Employee();
        updatedEmployee.setId(1);
        updatedEmployee.setName("李四");
        updatedEmployee.setGender("女");
        updatedEmployee.setBirthday("1990-02-02");
        updatedEmployee.setHireDate("2020-02-02");

        EmployeeDao.updateEmployee(updatedEmployee);

        Employee getEmployee = EmployeeDao.getEmployeeById(1);
        System.out.println(getEmployee.getName());

        EmployeeDao.deleteEmployee(1);
    }
}