仅选择唯一值

Question

Tabls是

ID  Count
1    30
2    30
3    10
4    15
5    10
6    25

我想要查询哪个会给我

4    15
6    25

结果

Answer 1

您可以使用NOT EXISTS：

SELECT ID,  Count
FROM dbo.TableName t1
WHERE NOT EXISTS
(
   SELECT 1 FROM dbo.TableName t2
   WHERE t1.ID <> t2.ID AND t1.Count = t2.Count
)

Demo

Answer 2

以下内容应选择您想要的内容：

SELECT t.ID, t.[Count] 
FROM Table t 
WHERE 
   (SELECT COUNT(*) FROM Table t1 WHERE t1.[Count] = t.[Count]) = 1

请注意，您应该在Table.[Count]上有一个索引。

Answer 3

您也可以使用分组声明

SELECT MIN(ID), Count
FROM Table
GROUP BY Count
HAVING COUNT(*) = 1

Answer 4

将HAVING与COUNT DISTINCT一起使用，以限制结果：

SELECT [Id], [Count]
FROM MyTable
WHERE [Count] IN (
    SELECT [Count]
    FROM MyTable
    GROUP BY [Count]
    HAVING COUNT(DISTINCT [Count]) = 1
)