java mysql的增删改查

import java.sql.*;

public class MySQLExample {
    static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
    static final String DB_URL = "jdbc:mysql://localhost/yourdatabase";
    static final String USER = "username";
    static final String PASS = "password";

    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            // 注册 JDBC 驱动
            Class.forName(JDBC_DRIVER);

            // 打开连接
            System.out.println("连接数据库...");
            conn = DriverManager.getConnection(DB_URL, USER, PASS);

            // 执行查询
            System.out.println("实例化Statement对象...");
            stmt = conn.createStatement();
            String sql;
            sql = "SELECT id, name, age FROM employees";
            ResultSet rs = stmt.executeQuery(sql);

            // 提取数据
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");

                System.out.print("ID: " + id);
                System.out.print(", 名称: " + name);
                System.out.println(", 年龄: " + age);
            }
            rs.close();

            // 插入记录
            sql = "INSERT INTO employees (name, age) VALUES ('张三', 30)";
            int rowsInserted = stmt.executeUpdate(sql);
            if (rowsInserted > 0) {
                System.out.println(rowsInserted + " 行插入成功!");
            }

            // 更新记录
            sql = "UPDATE employees SET age = 31 WHERE name = '张三'";
            int rowsUpdated = stmt.executeUpdate(sql);
            if (rowsUpdated > 0) {
                System.out.println(rowsUpdated + " 行更新成功!");
            }

            // 删除记录
            sql = "DELETE FROM employees WHERE name = '张三'";
            int rowsDeleted = stmt.executeUpdate(sql);
            if (rowsDeleted > 0) {
                System.out.println(rowsDeleted + " 行删除成功!");
            }

        } catch (SQLException se) {
            // 处理 JDBC 错误
            se.printStackTrace();
        } catch (Exception e) {
            // 处理 Class.forName 错误
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (stmt != null) stmt.close();
            } catch (SQLException se2) {
            }
            try {
                if (conn != null) conn.close();
            } catch (SQLException se) {
                se.printStackTrace();
            }
        }
        System.out.println("完成!");
    }
}