NodeJS study notes MongoDB module_node.js

1, opening analysis

This article is an extended knowledge article, because database operations will be used in the following articles, so let’s talk about it (Mongodb module) today.

(1), Introduction

MongoDB is a database based on distributed file storage. Written in C language. Designed to provide scalable, high-performance data storage solutions for WEB applications.

MongoDB is a high-performance, open source, schema-less document database, which is one of the more popular NoSql databases currently.

MongoDB is a product between a relational database and a non-relational database. It is the most feature-rich among non-relational databases and is most like a relational database. The data structure it supports is very loose and is a json-like bjson format, so it can store more complex data types. The biggest feature of Mongo is that the query language it supports is very powerful. Its syntax is somewhat similar to an object-oriented query language. It can almost implement most functions similar to single-table queries in relational databases, and it also supports indexing of data.

Traditional relational databases generally consist of three levels of concepts: database, table, and record. MongoDB consists of three levels: database, collection, and document. composition.

MongoDB has tables in relational databases, but there are no concepts of columns, rows, and relationships in collections, which reflects the characteristics of schema freedom.

(2), Features

It is characterized by high performance, easy deployment, easy use, and very convenient for storing data. The main functional features are:

1) Set-oriented storage, easy to store object type data.
2) Free mode.
3) Support dynamic query.
4) Supports full indexing, including internal objects.
5) Support query.
6) Support replication and failure recovery.
7) Use efficient binary data storage, including large objects (such as videos, etc.).
8) Automatically handle fragmentation to support scalability at the cloud computing level.
9) Supports RUBY, PYTHON, JAVA, C, PHP, C# and other languages.
10) The file storage format is BSON (an extension of JSON).
11) Accessible via the Internet.

(3), Installation and use

1. Download and unzip "mongodb" to the specified directory, as follows:

　2. There are two most important files: "Mongod.exe" and "Mongo.exe".

Mongod.exe ------ Used to connect to the mongo database server, that is, the server side.
Mongo.exe ------ Used to start the MongoDB shell, that is, the client.

2, step by step operation

　(1), create a new directory, for example: ">mongod -dbpath data/db".

(2), open the browser and enter: "http://127.0.0.1:27017/", you will see the following words:

　"You are trying to access MongoDB on the native driver port. For http diagnostic access, add 1000 to the port number", indicating success.

At this point, the MongoDB database service has been successfully started.

(3), create database------Enter CMD, type the command "mongo.exe" and the following interface will appear:

　(4), type the following command in the shell command window: "use bb" (the use command is used to switch the current database. If the database does not exist, a new one will be created first).

　(5), type the following command in the shell command window: "db.users.insert({"name":"bigbear","password":"12345678"})",

　(This command is to insert a piece of data into the users collection. If the users collection does not exist, a new one will be created first, and then the data will be inserted. The parameters are passed in in JSON format).

(6), type the following command in the shell command window: "db.users.find()" (display all data documents under the users collection), as shown below:

Pay attention to the "_id" in the picture. The system automatically assigns a unique primary key _id to each record.

Alright! The basic functions are available. If additional operations are needed later, we will gradually add them. Due to the limited space, we mainly talk about NodeJS operating Mongodb, so we will stop here for now.

Third, enter the topic and analyze examples

(1), npm install mongodb (download and place in the specified directory).

(2), we have already established the database and collection ("bb", "users")

Copy code The code is as follows:

 var mongodb = require("mongodb") ;
 var server = new mongodb.Server("localhost",27017,{
     auto_reconnect : true
 }) ;
 var conn = new mongodb.Db("bb",server,{
     safe : true
 }) ;
 conn.open(function(error,db){
     if(error) throw error ;
     db.collection("users",{
         safe : true
     },function(err,collection){
         if(err) throw err ;
         collection.find().toArray(function(e,docs){
             if(e) throw e ;
             console.log(docs) ;
         }) ;
     }) ;
 }) ;

运行结果如下：

复制代码 代码如下:

 [
     {
         _id: 54b3ce920dc20a3ba9607f
         name: 'bigbear',
         password: '12345678'
     }
 ]

四，总结一下

（1），熟练使用MongoDB数据库。
（2），理解与关系型数据库之间的差异化。
（3），通过上述的例子，掌握NodeJS如何操作MongoDB。
（4），强调一句话：如何设计“NoSQL”类型的数据库，思想很重要。