无法使用Node.js连接到mysql（express）

Question

Hello Stacksoverflowers,

I have a problem to connect my server.js file to Mysql via Express. I've already insatlled mysql and express via npm.

when i run my server.js

The only thing it says in my console (MacOS default terminal) is: "node server running now - using http://localhost:3000 " (I got no errors)

and my webpage also showing correct - "Node Server running - startpage" in the browser.

The problem is that they say nothing like "Connected to the MySQL server" or "Timeout: error messages" ?? (look at #3)

// Dan k

//#1
// My codes from server.js

const express = require('express');
const mysql = require('mysql');
const hostname = "localhost:";
const port = 3000;

//#2
// create connection to DB 
const connection = mysql.createConnection({
host: "localhost",
user: 'root',
password: 'root',
port: 3000
});

//#3
// Connect to DB
connection.connect(function(err) {
if (!err) {
console.log('Connected to the MySQL server.');
}
else if (err)
{
return console.error('Timeout: ' + err.message);
}
});


// Routing with Express
const app = express();

//#4
// Startpage (root)
app.get('/', function(request, response){
response.send('Node Server running - startpage...');
response.end();
})

connection.end();

//#5
app.listen(port, (err) => {
if(err) throw err;
console.log("node server running now - using http://"+(hostname)+ . 
(port)");
});

Answer 1

I got what is causing the issue. You are using the same port number 3000 to connect to your mysqlDB and at the same time using the same port to run your nodejs application. This does throw an error but it takes a really long time to throw the error. So the simple answer here is that the port that you are mentioning in your createConnection() method is incorrect and needs to be changed. This port should be port number on which your mysql DB is running. From the error it is clear that your mysql DB is not running on port 3306 . You can check this post to figure out which port is your mysql DB running on. https://serverfault.com/questions/116100/how-to-check-what-port-mysql-is-running-on . Below is a reference for you. Please see the comments.

// create connection to DB 
const connection = mysql.createConnection({
host: "localhost",
user: 'root',
password: 'root',
port: 3000 // You need to change this and put in the correct port number.
});