MongoDB---增删查改

• 新增（一条或多条）

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017";
const dbName = "demo";
const client = new MongoClient(url, { useUnifiedTopology: true });

client.connect(err => {
  const db = client.db(dbName);
  db.collection("student").insertOne(
    { name: "Cercei", age: 22 },
    (err, result) => {
      if (err) throw err;
      console.log("数据插入成功");
      client.close();
    }
  );
});

• 查找

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017";
const dbName = "demo";
const client = new MongoClient(url, { useUnifiedTopology: true });

client.connect(err => {
  const db = client.db(dbName);
  db.collection("student")
    .find({})
    .toArray((err, docs) => {
      if (err) throw err;
      console.log(docs);
      client.close();
    });
});

• 连接与查找数据库时间对比（主要时间耗费在数据库的连接上）

const MongoClient = require("mongodb").MongoClient;

const url = "mongodb://localhost:27017";
const dbName = "demo";
const client = new MongoClient(url, { useUnifiedTopology: true });

console.time("connect");
client.connect(err => {
  console.time("find");
  const db = client.db(dbName);
  db.collection("student")
    .find({})
    .toArray((err, docs) => {
      if (err) throw err;
      console.log(docs);
      console.timeEnd("connect"); //connect: 1053.064ms
      console.timeEnd("find"); //find: 22.595ms
      client.close();
    });
});