需要做一个循环，只针对我不能测试的类型，所以这是把我想象的工作，但这将是沿着这些路线的东西，这里可能有语法错误

$query = " SELECT movie_name,movie_id,genre FROM movies
    JOIN movie_genre ON movies.movie_id = movie_genre.movie_id
    JOIN genre ON movie_genre.genre_id = genre.genre_id
    WHERE movie.movie_id = ?";    

    $stmt = mysqli_prepare($conn, $query);
    $stmt->bind_param('i', $id);
    $stmt->execute();
    $result = $stmt->get_result();
    if(mysqli_num_rows($result) > 0 ){

    // if it's greater than zero, great, we have at least 1 movie.
    // but if it's greater than 1, then we know we have more than 1 genre

    while ($row = mysqli_fetch_assoc($result)) {
    echo 'movie_id:'.$row["movie_id"].'movie name:'.$row["movie_name"];
    break; // so it only runs through this loop once, instead of using limit
    }//end while

    if(mysqli_num_rows($result) > 1 ){
    // more than 1 genre so loop and print out just genres
    while ($row = mysqli_fetch_assoc($result)) {    
      echo $row["genre"];    
    }//end while
    }//end if more than 1 genre
    }//end if

你可以用 GROUP_CONCAT 以及 GROUP BY :

SELECT movie_name,movie_id, GROUP_CONCAT(genre SEPARATOR ' ') AS genre
FROM movies
JOIN movie_genre ON movies.movie_id = movie_genre.movie_id
JOIN genre ON movie_genre.genre_id = genre.genre_id
WHERE movie.movie_id = ?
GROUP BY movie_name,movie_id