use node.js Connect to MySQL database (easy to understand)

osc_ u9wft6hh 2021-01-21 10:15:36
use node.js node js connect


Preface :

I've been blogging for a few days , Today, I finally write for the first time , I hope you can correct the shortcomings .
This article code for Xiaobai may not understand , But I came from 0 Start to create a folder to run , It's no problem to write along
requirement :Navicat Basic table building !!!
requirement :Navicat Basic table building !!!
requirement :Navicat Basic table building !!!



One 、 The preparation of the instruments

1.mysql database +Navicat Visualization tools ( The database form has been created )

2.vscode ( The preparatory work is basically needless to say, basically there are )

3.node.js Environmental Science ( Its installation )

Two 、 preparation

1. Again vscode New folder , Right click the folder and select open in the integrated terminal

2. Enter the initialization command npm init -y

3. install express Third-party module :npm i express

4. install mysql Third-party module :npm i mysql

The installation is completed, as shown in the figure below :

 Insert picture description here

3、 ... and 、 Write code

newly build app.js file

const express = require('express') // introduce express modular 
const app = express() // Create examples 
const mysql = require('mysql') // introduce mysql modular 
// Create database connection Fill in the database information 
// Fill in your own database information !!!!!!!!!!!
const conn = mysql.createConnection({

user:'root',
password:'123456',
host:'localhost',
database:'node'
})
// Test connection 
conn.connect(err=>{

console.log(err,' If null It's a successful connection ');
})
// Turn on the server 
app.listen(3000,()=>{

console.log(' The server 3000 Open port .....');
})

Enter the folder to run node .\app.js

The following figure shows that the connection is successful
 Insert picture description here

The following is the operation of adding, deleting, modifying and querying , Take insert and query for example

1. Insert function

Add the following code above the open server code :

// Define routes ( To put it bluntly, it's the website ) 
app.get('/a',(req,res)=>{

let sqlStr = "INSERT INTO student ( s_no, s_name )VALUES(20150015,' Handsome than ')"
// perform mysql sentence 
conn.query(sqlStr,(err)=>{

console.log(err,' If null,sql Statement executed successfully ')
})
// The successful page displays 
res.send(' Insert the success ')
})

Restart the server , Go to the website localhost:3000/a see
Before insertion

 Insert picture description here

After inserting
 Insert picture description here

2. Query function

Add... After the code that inserts the function :

// Query information 
app.get('/find',(req,res)=>{

let sql = `SELECT * FROM student `
conn.query(sql,(err,results)=>{

// The returned query information is result Then display it on the page 
res.send(results)
})
})

Restart the server , Go to the website localhost:3000/find see
The query results are shown in the figure ( No, the order is messy ):

 Insert picture description here

Conclusion : thus node The connection to the database and part of the functions are displayed ( This is the author's first article , Sorry for the bad writing , Don't understand also can private letter )

版权声明
本文为[osc_ u9wft6hh]所创,转载请带上原文链接,感谢
https://javamana.com/2021/01/20210121100046653n.html

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