如何在PDO中使用if语句执行准备语句？

$dsn = "mysql:host=localhost;dbname=mydatabase";
$username = "username";
$password = "password";

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

$condition = "some condition";
$query = "";

if ($condition) {
    $query = "SELECT * FROM users WHERE id = :id";
} else {
    $query = "SELECT * FROM users WHERE name = :name";
}

$stmt = $pdo->prepare($query);

if ($condition) {
    $stmt->bindParam(':id', $id, PDO::PARAM_INT);
    $id = 1;
} else {
    $stmt->bindParam(':name', $name, PDO::PARAM_STR);
    $name = "John";
}

$stmt->execute();

while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    echo "ID: " . $row['id'] . ", Name: " . $row['name'] . "<br>";
}