下面的代码仅对一个参数有效，而对两个参数则无效。 有人可以帮我吗？提前致谢。

    $sql = "SELECT `users`.*,`data`.* 
    FROM users 
    INNER JOIN data 
    ON users.id = data.uid 
    WHERE users.name LIKE ? AND data.city LIKE ? "; 

    $stmt = $mysqli->prepare( $sql );
    $stmt->bind_param(ss,Phill,Amsterdam);
    $stmt->execute();
    $result = $stmt->get_result();

    while( $row = $result->fetch_assoc() ){ 
      echo $row['name'] . " / " . $row['city'];
    }