I'm new to web development. I bought a server on DigitalOcean, created a droplet and installed LAMP. I have a simple PHP script to connect to MySQL. Here's my PHP script(conn.php)

<?php
$servername = "xxx.xx.xx.xxx";
$username = "root";
$password = "mypassword";
try {
$conn = new PDO("mysql:host=$servername;dbname=mysql", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTRERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully";
}catch(PDOException $e) {
echo "Connection failed: " . $e->getMessage();
}
?>
Now, when I try to run on my browser "xxx.xx.xx.xxx/conn.php", it's printing

Connection failed: SQLSTATE[HY000] [2002] Connection refused