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我在名为 musics 的表中有 4 列 -'artist','genre', 'writer' , 'producer'.

我需要编写一个查询，如果没有与列名对应的值重复，它返回一个值 0 ；如果有重复的值，它应该返回一个值 1，对应于该列名。

任何帮助深表感谢

4

4 回答 4

2

为了Artist

select convert(bit,(count(1)-1))
from table_name
group by artist  -- <-- Replace artist with column name for which duplicate
于 2013-05-24T05:23:30.657 回答
2 
SELECT (COUNT(artist)   <> COUNT(DISTINCT artist))   artist,
       (COUNT(genre)    <> COUNT(DISTINCT genre))    genre,
       (COUNT(writer)   <> COUNT(DISTINCT writer))   writer,
       (COUNT(producer) <> COUNT(DISTINCT producer)) producer
FROM musics

另一个版本

SELECT 
( SELECT (COUNT(*) > 0) 
    FROM (SELECT 1 FROM musics GROUP BY artist HAVING COUNT(*) > 1) a 
) artist,
( SELECT (COUNT(*) > 0) 
    FROM (SELECT 1 FROM musics GROUP BY genre HAVING COUNT(*) > 1) g 
) genre,
( SELECT (COUNT(*) > 0) 
    FROM (SELECT 1 FROM musics GROUP BY writer HAVING COUNT(*) > 1) w 
) writer,
( SELECT (COUNT(*) > 0) 
    FROM (SELECT 1 FROM musics GROUP BY producer HAVING COUNT(*) > 1) p 
) producer

样本数据

|  artist |  genre |  writer |  producer |
------------------------------------------
| artist1 | genre1 | writer1 | producer1 |
| artist2 | genre2 | writer1 | producer2 |
| artist1 | genre3 | writer3 | producer3 |

样本输出：

| artist | genre | writer | producer |
--------------------------------------
|      1 |     0 |      1 |        0 |

SQLFiddle

于 2013-05-24T05:45:33.767 回答
1

使用具有指定列的 distinct 和另一个没有 distinct 的 select count 编写一个 select count 语句，并根据您的要求比较它们

于 2013-05-24T05:21:58.923 回答
1

您可以将 4 个不同的查询与 union 一起使用，每个查询必须包含 count(column name) + group by 子句

于 2013-05-24T05:41:09.310 回答