在NodeJS中使用then查询多个数据库调用

const Promise = require('bluebird'); // 使用bluebird库来提供Promise功能
const mysql = require('mysql');
const mongodb = require('mongodb');

// 创建MySQL数据库连接
const mysqlConnection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'password',
  database: 'mydatabase'
});

// 创建MongoDB数据库连接
const mongoClient = mongodb.MongoClient;
const mongoURL = 'mongodb://localhost:27017/mydatabase';

// 创建Promise对象
const mysqlPromise = new Promise((resolve, reject) => {
  // 执行MySQL查询操作
  mysqlConnection.query('SELECT * FROM users', (error, results) => {
    if (error) {
      reject(error);
    } else {
      resolve(results);
    }
  });
});

const mongoPromise = new Promise((resolve, reject) => {
  // 执行MongoDB查询操作
  mongoClient.connect(mongoURL, (error, client) => {
    if (error) {
      reject(error);
    } else {
      const db = client.db('mydatabase');
      const collection = db.collection('users');
      collection.find().toArray((error, results) => {
        if (error) {
          reject(error);
        } else {
          resolve(results);
        }
        client.close();
      });
    }
  });
});

// 使用Promise.all方法查询多个数据库调用
Promise.all([mysqlPromise, mongoPromise])
  .then(([mysqlResults, mongoResults]) => {
    console.log('MySQL Results:', mysqlResults);
    console.log('MongoDB Results:', mongoResults);
  })
  .catch(error => {
    console.error('Error:', error);
  });