function login($email,$password)

$outcome;
$conn;
$servername = ...
$username = ...
$password = ...
$database = ...

try {
    $conn = new PDO(...);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $conn->setAttribute( PDO::ATTR_EMULATE_PREPARES, FALSE );


} catch(PDOException $e) {
    $outcome = "Connection failed: " . $e->getMessage();
    return $outcome;
    die();
}

$sql = "SELECT * FROM `users` WHERE user_email = ?";
$stmt = $conn->prepare($sql);

$stmt->execute(array($email));

$user = $stmt->fetch(PDO::FETCH_ASSOC);

...