Javaを利用した倉庫管理システムの受注管理機能の開発

import java.sql.*;

public class OrderManagementSystem {
    private static final String DATABASE_URL = "jdbc:mysql://localhost:3306/mydb";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "password";

    public static void addOrder(String productName, int quantity) {
        try (Connection connection = DriverManager.getConnection(DATABASE_URL, USERNAME, PASSWORD);
             PreparedStatement statement = connection.prepareStatement("INSERT INTO orders (product_name, product_quantity) VALUES (?, ?)")) {
            statement.setString(1, productName);
            statement.setInt(2, quantity);
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void viewOrders() {
        try (Connection connection = DriverManager.getConnection(DATABASE_URL, USERNAME, PASSWORD);
             Statement statement = connection.createStatement();
             ResultSet resultSet = statement.executeQuery("SELECT * FROM orders")) {
            while (resultSet.next()) {
                int orderId = resultSet.getInt("order_id");
                String productName = resultSet.getString("product_name");
                int quantity = resultSet.getInt("product_quantity");

                System.out.println("Order ID: " + orderId);
                System.out.println("Product: " + productName);
                System.out.println("Quantity: " + quantity);
                System.out.println();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void updateOrder(int orderId, String productName, int quantity) {
        try (Connection connection = DriverManager.getConnection(DATABASE_URL, USERNAME, PASSWORD);
             PreparedStatement statement = connection.prepareStatement("UPDATE orders SET product_name = ?, product_quantity = ? WHERE order_id = ?")) {
            statement.setString(1, productName);
            statement.setInt(2, quantity);
            statement.setInt(3, orderId);
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void deleteOrder(int orderId) {
        try (Connection connection = DriverManager.getConnection(DATABASE_URL, USERNAME, PASSWORD);
             PreparedStatement statement = connection.prepareStatement("DELETE FROM orders WHERE order_id = ?")) {
            statement.setInt(1, orderId);
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        // 示例代码

        // 添加订单
        addOrder("商品A", 5);
        addOrder("商品B", 10);

        // 查看订单
        System.out.println("当前订单：");
        viewOrders();

        // 修改订单
        updateOrder(1, "商品C", 20);

        // 删除订单
        deleteOrder(2);

        // 再次查看订单
        System.out.println("修改后的订单：");
        viewOrders();
    }
}