Question

我试图运行此查询;

SELECT artist, song, track, album, album_id, art, COUNT(artist) AS artistCount FROM listening_artist GROUP BY artist ORDER BY COUNT(artist) DESC

哪种方法很好，但我希望它只使用数据库中的30个结果而不是完整数据库。

我已尝试过这个

SELECT artist, song, track, album, album_id, art, COUNT(artist) AS artistCount FROM listening_artist LIMIT 30 GROUP BY artist ORDER BY COUNT(artist) DESC

什么都不返回。

我不在此之后

SELECT artist, song, track, album, album_id, art, COUNT(artist) AS artistCount FROM listening_artist GROUP BY artist LIMIT 30 ORDER BY COUNT(artist) DESC

因为这个限制为时已晚。

的含义

从过去30首播放的歌曲中选择用户最常听的艺术家。

我的数据库

+------------+----------+---------+---------+------------+-------+
|   artist   |   song   |  track  |  album  |  album_id  |  art  |
+------------+----------+---------+---------+------------+-------+
| T-Swift    |  22      | *NULL*  |   Red   |  9282781   | URL   |
|            |          |         |         |            |       |
+------------+----------+---------+---------+------------+-------+

感谢任何帮助。谢谢！

Answer 1

正如评论中已经指出的那样，你的第二个查询没有返回任何结果，因为语法无效。

而是使用子选择来限制结果：

SELECT artist, song, track, album, album_id, art, COUNT(artist) AS artistCount
FROM (
       SELECT *
       FROM listening_artist
       LIMIT 30
     ) AS recent_listening_artist
GROUP BY artist
ORDER BY COUNT(artist) DESC

在子选择内，您可以添加其他排序，例如在时间戳上播放了一首歌。

您没有指定实际的DBMS，因此您可能需要稍微调整语法（这是MySQL），但它至少应该为您提供正确方向的提示。

请注意，这只会为每位艺术家提供一行，这使得输出中的曲目或专辑有点毫无意义。有关小型演示，另请参阅this MySQL fiddle。

SQL - 限制要分组的结果数量

1 个答案: