如何用php pdo从mysql中的store-procedure/function中获取返回值

$dsn = 'mysql:host=localhost;dbname=your_database;charset=utf8';
$username = 'your_username';
$password = 'your_password';

try {
    $pdo = new PDO($dsn, $username, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

$sql = "CALL your_stored_procedure(?, ?)";

$param1 = 'value1';
$param2 = 'value2';

$stmt = $pdo->prepare($sql);
$stmt->bindParam(1, $param1, PDO::PARAM_STR);
$stmt->bindParam(2, $param2, PDO::PARAM_STR);

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

$returnValue = $result['your_return_value_column_name'];

$pdo = null;