mongodb nodejs更新使用之前的值

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/mydatabase';

MongoClient.connect(url, function(err, client) {
  if (err) throw err;
  console.log('Connected to MongoDB');

  // 在这里执行更新操作
});

const db = client.db('mydatabase');
const collection = db.collection('mycollection');

const filter = { name: 'John' };
const update = { $set: { age: 30 } };

collection.updateOne(filter, update, function(err, result) {
  if (err) throw err;
  console.log('Document updated');
  client.close();
});

client.close();