12.11-526互联

import java.sql.*;

public class CRUDExample {

    // 数据库连接信息
    private static final String URL = "jdbc:mysql://localhost:3306/mydatabase";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";

    // 创建
    public void create(String name, int age) {
        try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
             PreparedStatement stmt = conn.prepareStatement("INSERT INTO users (name, age) VALUES (?, ?)")) {

            stmt.setString(1, name);
            stmt.setInt(2, age);

            int rowsAffected = stmt.executeUpdate();
            if (rowsAffected > 0) {
                System.out.println("成功创建用户：" + name);
            } else {
                System.out.println("创建用户失败！");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 查询
    public void retrieve() {
        try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
             Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery("SELECT * FROM users")) {

            System.out.println("用户列表：");
            while (rs.next()) {
                String name = rs.getString("name");
                int age = rs.getInt("age");
                System.out.println("姓名：" + name + "，年龄：" + age);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 更新
    public void update(String name, int newAge) {
        try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
             PreparedStatement stmt = conn.prepareStatement("UPDATE users SET age = ? WHERE name = ?")) {

            stmt.setInt(1, newAge);
            stmt.setString(2, name);

            int rowsAffected = stmt.executeUpdate();
            if (rowsAffected > 0) {
                System.out.println("成功更新用户 " + name + " 的年龄为：" + newAge);
            } else {
                System.out.println("更新操作失败！用户 " + name + " 不存在。");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 删除
    public void delete(String name) {
        try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
             PreparedStatement stmt = conn.prepareStatement("DELETE FROM users WHERE name = ?")) {

            stmt.setString(1, name);

            int rowsAffected = stmt.executeUpdate();
            if (rowsAffected > 0) {
                System.out.println("成功删除用户：" + name);
            } else {
                System.out.println("删除操作失败！用户 " + name + " 不存在。");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        CRUDExample example = new CRUDExample();

        // 创建示例数据
        example.create("Alice", 25);
        example.create("Bob", 30);
        example.create("Charlie", 35);

        // 查询数据
        example.retrieve();

        // 更新数据
        example.update("Bob", 32);

        // 查询更新后的数据
        example.retrieve();

        // 删除数据
        example.delete("Charlie");

        // 查询删除后的数据
        example.retrieve();
    }
}