A brief analysis of node connection database (express mysql)_node.js
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 ;
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 = ?' ;
connection.query(selectSql,[username],function(err,res){
¦ if(err){
¦ ¦ console.log('getUserbyUsername err:' + err) ;
¦ ¦ return ;
¦ }
¦ console.log('Get name success') ;
¦ callback(err,res) ;
}) ;
} ;
module.exports = User ;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 = ?' ;
connection.query(selectSql,[username],function(err,res){
¦ if(err){
¦ ¦ console.log('getUserbyUsername err:' + err) ;
¦ ¦ return ;
¦ }
¦ console.log('Get name success') ;
¦ callback(err,res) ;
}) ;
} ;
module.exports = User ;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>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.
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