try {
    $db_host = 'HOST';
    $db_username = 'USER';
    $db_password = 'PASS';

    //$dsn = "mysql:dbname=test;host={$db_host}";
    $dsn = "mssql:dbname=test;host={$db_host}";

    $conn = new PDO($dsn, $db_username, $db_password);
} catch (PDOException $e) {
    print "Error!: " . $e->getMessage() . "<br/>";
    die();
}