How to make MySQL database connection with Node.JS?

If you want to operate a MySQL database through a programming language like JavaScript (Node.js), you need to connect the MySQL database with the language first.

Therefore in this tutorial, I will show you how you can make a connection between JavaScript (Node.js) and MySQL DB.

Node.js MySQL database connection

Here we will use the npm mysql2 package to make connection with MySQL database. Let’s see how you can use this package –

First, install this package with the help of the following command.

npm install --save mysql2

After that, import this package

import mysql from 'mysql2';

The mysql2 package has a method called createConnection() that is used to create a connection with the MySQL database.

import mysql from 'mysql2';

const connection = mysql.createConnection({
    options
});

Database information

We have to put the database information inside the createConnection() method with the help of the Options.

Database name	my_test_db
Host of the DB	localhost
User of the DB	root
Password of the DB	Enter your DB password

import mysql from 'mysql2';

const connection = mysql.createConnection({
    host:'localhost',
    user:'root',
    password:'',
    database:'my_test_db'
});

Verify that the database is connected successfully

import mysql from 'mysql2';

const connection = mysql.createConnection({
    host:'localhost',
    user:'root',
    password:'',
    database:'my_test_db'
});

// Verify that the database is connected successfully
connection.connect((error) => {
    if(error){
        console.error(error);
        return;
    }
    console.log('The database is successfully connected.');
})

PS c:\#project\node-js\learn-node-js> node index.js
The database is successfully connected.

---

MySQL2 also supports Promise API

import mysql from 'mysql2/promise';

try{
    const connection = await mysql.createConnection({
        host:'localhost',
        user:'root',
        password:'',
        database:'my_test_db'
    });
}
catch(err){
    console.log(`${err.name}: ${err.message}`);
}

---

Promise/Non-promise connections from the same pool

MySQL2 also exposes a .promise() function on Pools, so you can create a promise/non-promise connections from the same pool.

import mysql from 'mysql2';

// Non-promise connection
const connection = mysql.createPool({
    host:'localhost',
    user:'root',
    password:'',
    database:'my_test_db'
});

// Promise connection
const connectionPromise = connection.promise();

// Query with non promise
connection.query('SQL query...', (err, row, fields) => {
    ...
});

// Query with Promise connection
connectionPromise.query('SQL query...')
.then(([row,fields]) => {
    ...
})
.catch(err => {
    ...
})