AWS Lambda在执行完函数后会自动关闭与MySQL数据库的连接，因此无需手动关闭。以下是一个基本的示例，演示了如何在AWS Lambda中使用MySQL：

const mysql = require('mysql');

exports.handler = (event, context, callback) => {
  const connection = mysql.createConnection({
    host: 'your_mysql_host',
    user: 'your_mysql_user',
    password: 'your_mysql_password',
    database: 'your_mysql_database'
  });

  connection.connect();

  connection.query('SELECT * FROM your_table', (error, results, fields) => {
    if (error) throw error;
    console.log(results);
    callback(null, 'Success');
  });

  // No need to manually close the connection,
  // as AWS Lambda automatically closes it
};