NodeJS -如何检查MySQL结果是否未定义/为空？

const mysql = require('mysql');

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'your_username',
  password: 'your_password',
  database: 'your_database'
});

connection.connect((err) => {
  if (err) throw err;
  console.log('Connected to MySQL database');
});

const query = 'SELECT * FROM your_table';

connection.query(query, (err, results) => {
  if (err) throw err;

  // 检查结果是否未定义或为空
  if (results === undefined || results.length === 0) {
    console.log('MySQL结果未定义或为空');
  } else {
    console.log('MySQL结果不为空');
    // 处理结果
  }
});