如何使用node.js从两个不同的数据库系统中检索数据？

// 引入MySQL和MongoDB的驱动程序
const mysql = require('mysql');
const MongoClient = require('mongodb').MongoClient;

// 配置MySQL和MongoDB的连接参数
const mysqlConfig = {
  host: 'mysql_host',
  user: 'mysql_user',
  password: 'mysql_password',
  database: 'mysql_database',
};

const mongoConfig = {
  url: 'mongodb_url',
  dbName: 'mongodb_database',
  collectionName: 'mongodb_collection',
};

// 建立MySQL和MongoDB的连接
const mysqlConnection = mysql.createConnection(mysqlConfig);
const mongoConnectionPromise = MongoClient.connect(mongoConfig.url);

// 执行查询操作
mysqlConnection.query('SELECT * FROM table', (mysqlError, mysqlResults) => {
  if (mysqlError) throw mysqlError;
  
  // 处理MySQL查询结果
  console.log('MySQL Results:', mysqlResults);
});

mongoConnectionPromise.then((mongoClient) => {
  const collection = mongoClient.db(mongoConfig.dbName).collection(mongoConfig.collectionName);
  return collection.find({}).toArray();
}).then((mongoResults) => {
  // 处理MongoDB查询结果
  console.log('MongoDB Results:', mongoResults);
}).catch((mongoError) => {
  throw mongoError;
});

// 关闭数据库连接
mysqlConnection.end();
mongoConnectionPromise.then((mongoClient) => {
  mongoClient.close();
});