Always gettings the same problem: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

Question

Error code on page:

SQL Error: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

Warning: Undefined variable $mysql in .../phplogin/register.php on line 11

Fatal error: Uncaught Error: Call to a member function prepare() on null in .../www/phplogin/register.php:11 Stack trace: #0 {main} thrown in .../phplogin/register.php on line 11

Code in register.php [variables like pw, pw2 and username are definded in the html part of the file, which i cant insert here]:

<?php
    if(isset($_POST['submit'])) {require("mysql.php");
        $stmt = $mysql->prepare("SELECT * FROM accounts WHERE USERNAME = :user");// Check username
        $stmt->bindParam(":user", $_POST['username']);
        $stmt->execute();
        $count = $stmt->rowCount();
        if($count == 0) {
            // Username not used
            if($_POST['pw'] == $_POST['pw2']) {
                //User anlegen
                $stmt = $mysql->prepare("INSERT INTO accounts (USERNAME, PASSWORD) VALUES (:user, :pw");
                $stmt->bindParam(":user", $_POST['username']);
                $hash = password_hash($_POST['pw'], PASSWORD_BCRYPT);
                $stmt->bindParam(":pw", $hash);
                $stmt->execute();
                echo "Dein Account wurde angelegt"; // Added account into database
            } else {
                echo "Passwörter stimmen nicht überein"; // pw and pw2 are not the same
            }
        } else {
            echo "Username bereits vergeben"; // Username used already
        }
    }
    ?>

Code in mysql.php:

<?php
$host = '[the host]';
$name = '[the database name]';
$user = '[the user]';
$password = '[the user password]';

try {
    $mysql = new PDO("mysql:host=§host;dbname=$name", $user, $password);
} catch (PDOException $e) {
    echo "SQL Error: ".$e->getMessage();
}
?>

I use the hoster bplaced on freestyle plan so i cant just restart the database servers.

I wrote this to create the tables: CREATE TABLE accounts (USERNAME varchar(255) UNIQUE, PASSWORD varchar(255));