Using nodejs to operate MySQL

One , Use of modules

1. Install the module

npm i axios -S

2. The import module

var axios = require('axios');

3. Using modules

axios.get(url)
.then(res=>res.data)
.catch(err=>err)

Two , Custom module

1. A file is a module

Define modules

module.exports = {
  max:function(a,b){return a}
  min:(a,b)=>b
}

2. The import module

const utils =  require("./utils")
utils.max(15,20)

3. Using modules

var  {max,min}  =require("./utils.js")
min(5,20) 

3、 ... and 、fs Document processing

1. Import file module

var fs = require('fs')

2. Read

var re = fs.readyFileSync(url,"utf-8")

fs.readyFile(url,"utf-8",function(err,data){})

3. write in

fs.writeFileSync(url,data)

fs.writeFile(url,data,function(err){})

Four 、http The server

1. Import

var http =  require("http");
var url = require("url")//  Address resolution 

2. Create a server

var server =  http.createServer(function(req,res){
 var Url = url.parse(req.url);// analysis url
res.status = 200;//  Set status code 
res.setHeader("Content-Type","application/json")
res.end(`{}`}
})

3. Listen and start

server.listen("8888",function(){
    console.log(" The server is up ")
})

5、 ... and 、mysql install

1. Configure environment variables

C:\Program Files\MySQL\MySQL Server 5.7\bin  

2. initialization

mysqld -install
mysqld --initialize

3. Start the server

net start mysql 

4. Sign in

mysql -u root -p

6、 ... and ,mysql command

1. Inquire about

select * from user where 1

2. Querying a user

select * from user where name='zeng8' and password='zmm123'

3. The score is greater than 500

select * from user where score>500

4. Query all users , from 1 Began to intercept 2 strip

select * from user where 1 limit 1,2

5. Query all users , Sort by score , Ascending acs Descending desc

select * from user where 1 order by score asc