'use strict';

var MongoClient = require('mongodb').MongoClient;

MongoClient.connect( 'mongodb://127.0.0.1:27017/accounting', function (err, connection) {

var collection = connection.collection('customers');

var doFind = function (callback) { collection.find().toArray(function (err, documents) {
        console.dir(documents);
        callback();
      });

};
var doInsert = function (i) { if (i < 20) {
var value = Math.floor(Math.random() * 10); collection.insert(
{'n': '#' + i, 'v': value}, function (err, count) {
        doInsert(i + 1);
      });
} else {
console.log();
console.log('Inserted', i, 'documents:'); doFind(function () {
      doUpdate();
    });
} };
var doUpdate = function () {

collection.update(

{'v': {'$gt': 5}},
{'$set': {'valuable': true}}, {'multi': true},

function (err, count) {

console.log();
console.log('Updated', count, 'documents:');

doFind(function () {
collection.remove({}, function () { connection.close();
});
});
});
};
    doInsert(0);
  });