Question

我试图同时显示MIN＆amp; MAX加入几张表格以获取信息。我得到了MIN＆amp; MAX但它显示我其他字段的错误信息。

SELECT
    SONG.SONG_NAME,
    ALBUM.ALBUM_NAME,
    ARTIST.ARTIST_NAME,
    MAX(SONG.LENGTH_SECONDS) AS LENGTH
FROM SONG
    JOIN ALBUM ON ALBUM.ALBUM_ID = SONG.ALBUM_ID
    JOIN ARTIST ON ARTIST.ARTIST_ID = SONG.ARTIST_ID
UNION
SELECT
    SONG.SONG_NAME,
    ALBUM.ALBUM_NAME,
    ARTIST.ARTIST_NAME,
    MIN(SONG.LENGTH_SECONDS)
FROM SONG
    JOIN ALBUM ON ALBUM.ALBUM_ID = SONG.ALBUM_ID
    JOIN ARTIST ON ARTIST.ARTIST_ID = SONG.ARTIST_ID;

这些是我在查询中得到的结果：

| SONG_NAME              | ALBUM_NAME                | ARTIST_NAME    | LENGTH |
+------------------------+---------------------------+----------------+--------+
| Fluorescent Adolescent | Favourite Worst Nightmare | Arctic Monkeys |    390 |
| Fluorescent Adolescent | Favourite Worst Nightmare | Arctic Monkeys |    177 |

Answer 1

您可以删除MAX＆amp;从SELECT中选择MIN并添加TOP 1。然后添加ORDER BY SONG.LENGTH_SECONDS以获得最短的歌曲和ORDER BY SONG.LENGTH_SECONDS DESC以获得最长的歌曲。

SELECT TOP 1
    SONG.SONG_NAME,
    ALBUM.ALBUM_NAME,
    ARTIST.ARTIST_NAME,
    SONG.LENGTH_SECONDS AS LENGTH
FROM SONG
    JOIN ALBUM ON ALBUM.ALBUM_ID = SONG.ALBUM_ID
    JOIN ARTIST ON ARTIST.ARTIST_ID = SONG.ARTIST_ID
ORDER BY SONG.LENGTH_SECONDS DESC
UNION
SELECT TOP 1
    SONG.SONG_NAME,
    ALBUM.ALBUM_NAME,
    ARTIST.ARTIST_NAME,
    SONG.LENGTH_SECONDS AS LENGTH
FROM SONG
    JOIN ALBUM ON ALBUM.ALBUM_ID = SONG.ALBUM_ID
    JOIN ARTIST ON ARTIST.ARTIST_ID = SONG.ARTIST_ID;
ORDER BY SONG.LENGTH_SECONDS

Answer 2

假设您正在为每位艺术家和专辑寻找歌曲的最小和最长持续时间，并为这些歌曲获取歌曲名称

您可以使用按SONG.ALBUM_ID，ALBUM.ALBUM_NAME，ARTIST.ARTIST_NAME分组的联合加入歌曲以获得正确的歌曲名称

select song.song_name, t.ALBUM_NAME, t.ARTIST_NAME, t.LENGTH
from song
inner join (
  SELECT 
      SONG.ALBUM_ID
      ALBUM.ALBUM_NAME,
      ARTIST.ARTIST_NAME,
      MAX(SONG.LENGTH_SECONDS) AS LENGTH
  FROM SONG
      JOIN ALBUM ON ALBUM.ALBUM_ID = SONG.ALBUM_ID
      JOIN ARTIST ON ARTIST.ARTIST_ID = SONG.ARTIST_ID 
  GROUP BY SONG.ALBUM_ID,ALBUM.ALBUM_NAME, ARTIST.ARTIST_NAME
) T on song.album_id = t.album_id and t.LENGTH = song.LENGTH_SECONDS 

UNION 

select song.song_name, t.ALBUM_NAME, t.ARTIST_NAME, t.LENGTH
from song
inner join (
  SELECT 
      SONG.ALBUM_ID
      ALBUM.ALBUM_NAME,
      ARTIST.ARTIST_NAME,
      MIN(SONG.LENGTH_SECONDS) AS LENGTH
  FROM SONG
      JOIN ALBUM ON ALBUM.ALBUM_ID = SONG.ALBUM_ID
      JOIN ARTIST ON ARTIST.ARTIST_ID = SONG.ARTIST_ID 
  GROUP BY SONG.ALBUM_ID,ALBUM.ALBUM_NAME, ARTIST.ARTIST_NAME
) T on song.album_id = t.album_id and t.LENGTH = song.LENGTH_SECONDS

MIN＆amp; MAX加几个JOINS

2 个答案: