PHP Connection failed SQLSTATE HY000 2002 Connection refused

Question

I am trying to connect MySQL Database which is on PHPMyAdmin.using PHP. I am using MAMP to host the database, the connection I am trying to use is this:

<?php
$servername = "127.0.0.1";
$username = "root";
$password = "root";

try {
    $conn = new PDO("mysql:host=$servername;dbname=AppDatabase", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully"; 
}
catch(PDOException $e)
{
    echo "Connection failed: " . $e->getMessage();
}
?>

I keep receiving this error when I try to test if the connection is working or not using postman:

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

How can I make this work?