Question

这里我有一个名为CoreTracks的表：

+---------+-----------------+----------+----------+----------+---------+
| TrackId |       URI       | ArtistID |  Title   | FileSize | BitRate |
+---------+-----------------+----------+----------+----------+---------+
|  1      | /home/music/... |   234    | atune    |  8958223 |   192   |
|  2      | /home/music/... |   427    | goodsong |  6954373 |   192   |
|  3      | /home/music/... |   427    | goodsong |  4695698 |   128   |
|  4      | /home/music/... |   427    | goodsong |  5839962 |   160   |
|  5      | /home/music/... |   427    | goodsong |  4695698 |   128   |
|  6      | /home/music/... |   522    | another  |  3458859 |   128   |
+---------+-----------------+----------+----------+----------+---------+

我想要检索的是：

+---------+-----------------+----------+----------+----------+---------+
| TrackId |       URI       | ArtistID |  Title   | FileSize | BitRate |
+---------+-----------------+----------+----------+----------+---------+
|  3      | /home/music/... |   427    | goodsong |  4695698 |   128   |
|  4      | /home/music/... |   427    | goodsong |  5839962 |   160   |
|  5      | /home/music/... |   427    | goodsong |  4695698 |   128   |
+---------+-----------------+----------+----------+----------+---------+

我正在尝试删除基于具有相同标题，相同艺术家ID和不同轨道ID的重复项，同时不返回具有最高比特率和最高文件大小的条目。

到目前为止我所拥有的是：

SELECT * FROM CoreTracks 
WHERE Title = Title AND ArtistID = ArtistID 
AND BitRate != (SELECT MAX(BitRate) FROM CoreTracks WHERE Title = Title AND ArtistID = ArtistID) 
AND FileSize != (SELECT MAX(FileSize) FROM CoreTracks WHERE Title = Title AND ArtistID = ArtistID);

返回每个曲目。我缺少什么才能使这个查询有效？

Answer 1

这将得到反转（即跳过重复）：

SELECT c1.*
  FROM CoreTracks c1
      ,(SELECT Title, ArtistID, MAX(FileSize) AS maxFileSize, MAX(BitRate) maxBitRate
          FROM CoreTracks
          GROUP BY Title, ArtistID) c2
  WHERE c1.Title = c2.Title
    AND c1.ArtistID = c2.ArtistID
    AND (c1.FileSize = c2.maxFileSize OR c1.BitRate = c2.maxBitRate)

重复：

SELECT c1.*
  FROM CoreTracks c1
      ,(SELECT Title, ArtistID, MAX(FileSize) AS maxFileSize, MAX(BitRate) maxBitRate
          FROM CoreTracks
          GROUP BY Title, ArtistID) c2
  WHERE c1.Title = c2.Title
    AND c1.ArtistID = c2.ArtistID
    AND (c1.FileSize != c2.maxFileSize AND c1.BitRate != c2.maxBitRate)

Answer 2

按标题从Group中选择max（trackId），按BitRate asc排序ArtistID - 然后将其包含在trackId的另一个select中？

Answer 3

SELECT A.* FROM CoreTracks A, CoreTracks B 
WHERE A.Title = B.Title AND A.ArtistID = B.ArtistID AND A.trackId != B.trackId
HAVING A.BitRate != MAX(A.BitRate) AND A.FileSize != MAX(A.FileSize);

尚未测试但应该有效。

Answer 4

尝试自联接而不是普通查询。我没试过。

从单行中选择重复项？

4 个答案: