Question

我的查询是针对我的SQL Server运行的：

SELECT SongUID, ArtistAlias, TitleAlias, Quality 
FROM 
    (SELECT 
        ROW_NUMBER() OVER(PARTITION BY ArtistAlias, TitleAlias 
                          ORDER BY Quality Desc) AS rn, * 
     FROM KaraokeLibrary) dt
WHERE rn = 1

但是我不能让它在SQL Server CE 4下运行（不支持ROW_NUMBER()且不支持OVER...PARTITION）。

我已经能够通过此查询在SQL Server CE中“关闭”：

SELECT SongUID, ArtistAlias, TitleAlias, Quality 
FROM KaraokeLibrary A
WHERE Quality >= 0 AND Quality IN (SELECT MAX(Quality) 
                                 FROM KaraokeLibrary B 
                                 WHERE B.ArtistAlias = A.ArtistAlias 
                                   AND B.TitleAlias = A.TitleAlias)
ORDER BY ArtistAlias, TitleAlias

但仍然列出重复的艺术家/头衔 - 不能有这个。

任何SQL Server CE专家都会在这个问题上为我提供一些查询魔力吗？

更新：为了进一步解释 - 我得到的最终结果是给定的数据如下：

SongUID  ArtistAlias  TitleAlias  Quality
    10,    'Artist1',    'Title1',    3
    11,    'Artist1',    'Title1',    2
    12,    'Artist1',    'Title1',    1
    13,    'Artist2',    'Title1',    3
    14,    'Artist2',    'Title1',    2
    15,    'Artist2',    'Title1',    1
    16,    'Artist2',    'Title2',    2
    18,    'Artist2',    'Title2',    1
    19,    'Artist2',    'Title2',    3
    20,    'Artist2',    'Title2',    3
    21,    'Artist2',    'Title2',    1

我想将此归还：

10, 'Artist1', 'Title1', 3
13, 'Artist2', 'Title1', 3
20, 'Artist2', 'Title2', 3

Answer 1

您也可以像这样编写查询：

SELECT  SongUID, ArtistAlias, TitleAlias, Quality
From KaraokeLibrary kl
where quality > 0 and
      songuid = (select top ( 1 ) songuid
                 from Karokelibrary kl2
                 WHERE kl.ArtistAlias=kl2.ArtistAlias AND kl.TitleAlias=kl2.TitleAlias
                 order by quality desc
                )

（注意：你不需要“top（1）”中的空格。这是我上传解决方案的唯一方法。）

旧版本的SQL CE可能不支持top。

Answer 2

您是否尝试过使用子查询：

select k1.SongUID,
  k1.ArtistAlias, 
  k1.TitleAlias,
  k1.quality
from KaraokeLibrary k1
inner join 
(
  select max(quality) maxQuality,
    ArtistAlias, TitleAlias
  from KaraokeLibrary
  where  Quality >= 0
  group by ArtistAlias, TitleAlias
) k2
  on k1.ArtistAlias = k2.ArtistAlias
  and k1.TitleAlias = k2.TitleAlias
  and k1.quality = k2.maxQuality
where  k1.Quality >= 0

请参阅SQL Fiddle with Demo

如果您有songuid的多个版本，则可以使用聚合：

select max(k1.SongUID),
  k1.ArtistAlias, 
  k1.TitleAlias,
  k1.quality
from KaraokeLibrary k1
inner join 
(
  select max(quality) maxQuality,
    ArtistAlias, TitleAlias
  from KaraokeLibrary
  where  Quality >= 0
  group by ArtistAlias, TitleAlias
) k2
  on k1.ArtistAlias = k2.ArtistAlias
  and k1.TitleAlias = k2.TitleAlias
  and k1.quality = k2.maxQuality
where  k1.Quality >= 0
group by k1.ArtistAlias, 
  k1.TitleAlias,
  k1.quality

请参阅SQL Fiddle with Demo

需要帮助将SQL Server查询转换为SQL Server Compact Edition

2 个答案: