I recently installed php7.4-fpm (FPM/FastCGI). But I'm not able to connect to MySQL database.

I'm using the following configuration. Note my database has no password. Tried 'localhost', '127.0.0.1', 'http://127.0.0.1:3306', '127.0.0.1:3306', in DB_SERVER setting but no luck.

<?php
/* Database credentials. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
define('DB_SERVER', '127.0.0.1');
define('DB_USERNAME', 'root');
define('DB_PASSWORD', '');
define('DB_NAME', 'republic');

/* Attempt to connect to MySQL database */
$link = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME);

// Check connection
if($link === false){
    die("Oops! Something went wrong. Please try again later.");
}
?>