nodejs连接mongodb数据库实现增删改查

var MongoClient = require("mongodb").MongoClient;
var DB_URL = "mongodb://localhost:27017/chm";

function insertData(db)
{
  var devices = db.collection('');
  var data = {"name":"node","age":22,"addr":"nb","addTime":new Date()};
  devices.insert(data,function(error, result){
    if(error)
    {
      console.log('Error:'+ error);
    }else{

      console.log(result.result.n);
    }
    db.close();
  });
}

 
MongoClient.connect(DB_URL, function(error, db){
  console.log('连接成功!');
  insertData(db);
});

var mongodb = require('mongodb')
var MongoClient = require('mongodb').MongoClient;
var DB_CONN_STR = 'mongodb://localhost:27017/chm'; 

var selectData = function(db, callback) { 
 //连接到表 
 var collection = db.collection('');
 //查询数据
 var whereStr = {"name":'node'};
 collection.find(whereStr,function(error, cursor){
  cursor.each(function(error,doc){
    if(doc){
      //console.log(doc);
      if (doc.addTime) {
        console.log("addTime: "+doc.addTime);
      }
    }
  });

 });

}

MongoClient.connect(DB_CONN_STR, function(err, db) {
 console.log("连接成功！");
 selectData(db, function(result) {
  console.log(result);
  db.close();
 });
});

var MongoClient = require("mongodb").MongoClient;
var DB_URL = "mongodb://localhost:27017/chm";

MongoClient.connect(DB_URL, function(error, db){
  console.log("连接成功!");
  updateData(db);
});

function updateData(db)
{
  var devices = db.collection('');
  var whereData = {"name":"node"}
  var updateDat = {$set: {"age":26}}; //如果不用$set，替换整条数据
  devices.update(whereData, updateDat, function(error, result){
    if (error) {
      console.log('Error:'+ error);
    }else{
      console.log(result);
    }
    db.close();
  });
}

var MongoClient = require('mongodb').MongoClient;
var DB_URL = "mongodb://localhost:27017/chm";

MongoClient.connect(DB_URL, function(error, db){
  console.log("连接成功");
  deleteData(db);
});

function deleteData(db)
{
  var devices = db.collection('');
  var data = {"name":"node"};
  devices.remove(data, function(error, result){
    if (error) {
      console.log('Error:'+ error);
    }else{
      console.log(result.result.n);
    }
    db.close();
  })
}

var MongoClient = require("mongodb").MongoClient;
var DB_URL = "mongodb://localhost:27017/chm";

MongoClient.connect(DB_URL, function(error,db){
  console.log("连接成功!");
  callProcess(db)
});

function callProcess(db)
{
  db.eval("get__count()",function(error, result){
    if (error) {
      console.log(error);
    }else{
      console.log("count:"+result);
    }
    db.close();
  });
}