Node.js MongoDB Creating Database giving error [duplicate]

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/mydb";

MongoClient.connect(url, function(err, db) {
  if (err) 
  {
  throw err;
  }
  console.log("Database created!");
  db.close();
});

This is the error I am getting when executing this code in nodejs and trying to create a database, I was going through the tutorial in w3school, please help to solve this error--

    C:\Users\n.patel\Desktop\Promotion\nodejs\application4success>node mymongodb.js

C:\Users\n.patel\Desktop\Promotion\nodejs\application4success\node_modules\mongodb\lib\mongo_client.js:415
          throw err
          ^
 MongoError: failed to connect to server [localhost:27017] on first connect [MongoError: connect ECONNREFUSED 127.0.0.1:27017]
    at null.<anonymous> (C:\Users\n.patel\Desktop\Promotion\nodejs\application4success\node_modules\mongodb\node_modules\mongodb-core\lib\topologies\server.js:3
29:35)
    at emitOne (events.js:77:13)
    at emit (events.js:169:7)
    at null.<anonymous> (C:\Users\n.patel\Desktop\Promotion\nodejs\application4success\node_modules\mongodb\node_modules\mongodb-core\lib\connection\pool.js:280
:12)
    at g (events.js:260:16)
    at emitTwo (events.js:87:13)
    at emit (events.js:172:7)
    at Socket.<anonymous> (C:\Users\n.patel\Desktop\Promotion\nodejs\application4success\node_modules\mongodb\node_modules\mongodb-core\lib\connection\connection.js:187:49)
    at Socket.g (events.js:260:16)
    at emitOne (events.js:77:13)