Noodjs (KOA) +mysql build server environment and basic additions and deletions to the operation

Create a project file manually

1. Under the specified directory, right-click to create the project folder.
2. Use the GIT init command to turn the contents of this file into a file that can be versioned by git.
3. Execute "npm init-y" command, create Package.json file, initialize
4. Execute the NPM init KOA command, install KOA, and a Package-lock.json file will be generated under the project path.

Create server

1. Create a app.js file, and then copy the following code in

const Koa = require(‘koa‘);const app = new Koa();const main = ctx => {    ctx.response.body = ‘Hello World‘;}app.use(main);app.listen(3000);

Then execute the following command

node app.js

Finally in the browser open http://127.0.0.1:3000/this connection, if you see the familiar "Hello world" that your server has been successfully started.

Connecting to a database

Here I am using the Mysql,mac on the MySQL installation can refer to my this Mac on the N-times install and uninstall MySQL.
Install the Nodejs MySQL package first

npm install mysql

To create a connection:

const Koa = require(‘koa‘);var mysql = require(‘mysql‘); //导入模块const app = new Koa();var connection = mysql.createConnection({   host:‘http://localhost‘,   user:‘root‘,   port: ‘3306‘,   password:‘‘,   database:‘test‘});connection.connect();  //创建连接

manipulating databases

Attach your own SQL statement to create the table

create table  record( id INT NOT NULL   AUTO_INCREMENT,userId INT NOT NULL,text TEXT,foreign key(userId) references user(id),PRIMARY KEY(id));create table record_img( id  INT NOT NULL   AUTO_INCREMENT,recordId INT NOT NULL,imgSrc varchar(255) NOT NULL,foreign key(recordId) references record(id),PRIMARY KEY(id));create table user( id INT NOT NULL   AUTO_INCREMENT,nickName varchar(200)  NOT NULL,gender varchar(200),city varchar(200),province  varchar(200),country  varchar(200),birthday DATE,PRIMARY KEY(id));

Basic operations on a database

• Inquire

var sql =‘select * from user‘;connection.query(sql,function(err,result){    if(err){        console.log(‘[SELECT ERROR] - ‘,err.message);        return;    }    console.log(‘--------------------------SELECT----------------------------‘);    console.log(result);    console.log(‘------------------------------------------------------------\n\n‘);});

• Modify

connection.connect();  //创建连接var sql =‘update user set nickName = ? where id = ?‘;var sqlpar=[‘julieCopy‘,1];connection.query(sql,sqlpar,function(err,result){    if(err){        console.log(‘[UPDATE ERROR] - ‘,err.message);        return;    }    console.log(‘--------------------------SELECT----------------------------‘);    console.log(‘UPDATE affectedRows‘,result.affectedRows);    console.log(‘------------------------------------------------------------\n\n‘);});connection.end();

• Increase

connection.connect();  //创建连接var addSql =‘insert into  user (nickName) values(?)‘;var addPar= [‘jessicacopy‘];connection.query(addSql,addPar,function(err,result){    if(err){        console.log(‘[insert ERROR] - ‘,err.message);        return;    }    console.log(‘--------------------------SELECT----------------------------‘);    console.log(‘UPDATE affectedRows‘,result.affectedRows);    console.log(‘------------------------------------------------------------\n\n‘);});connection.end();

• Delete

connection.connect();  //创建连接var delSql =‘delete from  user where id = 2‘;connection.query(delSql,function(err,result){   if(err){       console.log(‘[UPDATE ERROR] - ‘,err.message);       return;   }   console.log(‘--------------------------SELECT----------------------------‘);   console.log(‘UPDATE affectedRows‘,result.affectedRows);   console.log(‘------------------------------------------------------------\n\n‘);});connection.end();

Noodjs (KOA) +mysql build server environment and basic additions and deletions to the operation