A brief analysis of node connection database (express mysql)

A brief analysis of node connection database (express mysql)_node.js

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Release： 2016-05-16 15:28:51

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The operation is under the environment of ubuntu system, and the process will be simply recorded.

First use apt-get to install the database, type the command sudo apt-get install mysql-server, press Enter all the way, and then set the database root password on an interface

We need to create something in the database. Type mysql -uroot -p××××× to enter the sql console.

1. First create a data set create database databasename;

2.use database databasename ；

3. Create a table (create a very simple one here, only auto-increment id, username and password)

 create table user_info (                          
   id int(11) not null auto_increment,
   username varchar(30) not null,
   password varchar(30) not null,
   primary key ( id )
  )ENGINE=InnoDB DEFAULT CHARSET=utf8 ;

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4. Insert a piece of data insert into user_info values(1,'mtjss2','123456') ;

The following is the part of node

Create a folder, such as myapp, and after npm init, the dependency folder of node_modules will be included

Use npm install --save to install the following dependencies

1.express

2.mysql

3.body-parser (used to parse post parameters)

Since Express does not seem to have its own database package, you usually create a new models folder and then write the logic of the database. If you just want a simple test, you can write it directly in app.js

For example, here is a logical encapsulation class of user.js under models. Currently, there is only one method to obtain user information through username. Others can be added later

var mysql = require('mysql') ;                                                                                      
  //connection config
  var connection = mysql.createConnection({
    host : 'localhost' ,
    user : 'root' ,
    password : '123456' ,
    database : 'my_box'
 });
 function User(user){
   this.username = user.username ;
   this.password = user.password ;
 }
 User.getUserbyUsername = function(username,callback){
   var selectSql = 'select * from user_info where username = &#63;' ;
   connection.query(selectSql,[username],function(err,res){
   &brvbar;  if(err){
   &brvbar;  &brvbar;  console.log('getUserbyUsername err:' + err) ;
   &brvbar;  &brvbar;  return ;
   &brvbar;  }
   &brvbar;  console.log('Get name success') ;
   &brvbar;  callback(err,res) ;
   }) ;
 } ;
 module.exports = User ;

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Post again app.js does not write routing for the time being, it is the processing of / and /reg methods

 var mysql = require('mysql') ;                     
  //connection config
  var connection = mysql.createConnection({
    host : 'localhost' ,
    user : 'root' ,
    password : '123456' ,
    database : 'my_box'
  });
 function User(user){
   this.username = user.username ;
   this.password = user.password ;
 }
 User.getUserbyUsername = function(username,callback){
   var selectSql = 'select * from user_info where username = &#63;' ;
   connection.query(selectSql,[username],function(err,res){
   &brvbar;  if(err){
   &brvbar;  &brvbar;  console.log('getUserbyUsername err:' + err) ;
   &brvbar;  &brvbar;  return ;
   &brvbar;  }
   &brvbar;  console.log('Get name success') ;
   &brvbar;  callback(err,res) ;
   }) ;
 } ;
 module.exports = User ;

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The main page index.html is under the views folder. There is no code, but I will post it here

<!DOCTYPE html>
<html>
<head>
  <title>my box</title>
</head>
<body>
  <form action="/reg" method="post">
    <input type="text" name="username"/>
    <input type="submit" value="submit"/>
  </form>
</body>
</html>

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After starting with node app.js, just access localhost:3000 in the browser. Enter the user name in the database in the input to get the data.

ps: What are the advantages and disadvantages of using Node.js?

Node.js advantages: 1. It uses event-driven, asynchronous programming and is designed for network services. In fact, Javascript's anonymous functions and closure features are very suitable for event-driven and asynchronous programming. Moreover, JavaScript is easy to learn, and many front-end designers can quickly start doing back-end design. 2. Node.js' non-blocking mode IO processing brings Node.js high performance and outstanding load capacity with relatively low system resource consumption, making it very suitable for use as a middle-tier service that relies on other IO resources. 3. Node.js is lightweight and efficient, and can be considered a perfect solution for real-time application systems in data-intensive distributed deployment environments. Node is great for situations where you anticipate there may be high traffic before responding to the client, but the required server-side logic and processing isn't necessarily a lot.

Node.js Disadvantages: 1. Low reliability 2. Single process, single thread, only supports single-core CPU, and cannot fully utilize multi-core CPU servers. Once this process crashes, the entire web service crashes.