connect node.js to mysql code example

Example 1: php connect to mysql

$servername = "localhost";
$username = "username";
$password = "password";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";


Simplified

$conn = mysqli_connect('localhost', 'username', 'password');
$database = mysqli_select_db($conn, 'database');

Example 2: connect nodejs to mariadb

const mariadb = require('mariadb');
const pool = mariadb.createPool({
     host: 'mydb.com', 
     user:'myUser', 
     password: 'myPassword',
     connectionLimit: 5
});
async function asyncFunction() {
  let conn;
  try {
	conn = await pool.getConnection();
	const rows = await conn.query("SELECT 1 as val");
	console.log(rows); //[ {val: 1}, meta: ... ]
	const res = await conn.query("INSERT INTO myTable value (?, ?)", [1, "mariadb"]);
	console.log(res); // { affectedRows: 1, insertId: 1, warningStatus: 0 }

  } catch (err) {
	throw err;
  } finally {
	if (conn) return conn.end();
  }
}

Example 3: how to manage a db connection in javascript

//put these lines in a seperate file
const mysql = require('mysql2');

const connection = mysql.createPool({
    host: "localhost",
    user: "",
    password: "",
    database: ""
    // here you can set connection limits and so on
});

module.exports = connection;

//put these on destination page
const connection = require('../util/connection');

async function getAll() {
    const sql = "SELECT * FROM tableName";
    const [rows] = await connection.promise().query(sql);
    return rows;
} 
exports.getAll = getAll;

Example 4: use nodejs mysql

var mysql      = require('mysql');var connection = mysql.createConnection({  host     : 'localhost',  user     : 'me',  password : 'secret',  database : 'my_db'}); connection.connect(); connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {  if (error) throw error;  console.log('The solution is: ', results[0].solution);}); connection.end();