Question

假设我有一个看起来像这样的值表：

   Sample_Number | 
-------------------
    1             |
    1             |
    2             |
    3             |
    3             |
    4             |
    5             |

如何编写SELECT语句以返回恰好发生2次的最大样本数？在示例数据中，我要查找的值为3。

我想可能会有很多答案 - 我对没有内部选择的解决方案特别感兴趣并使用Having子句（如果可能的话）。

Answer 1

我确信有一种更简单的方法可以做到这一点，但你可以通过提取所有Sample_Number只有两个条目并拉出这些值的MAX()来实现这一目标：

;With Cte As
(
    Select  Sample_Number
    From    Test
    Group By Sample_Number
    Having  Count(Sample_Number) = 2
) 
Select  Max(Sample_Number)
From    Cte

Answer 2

您可以使用此查询：

SELECT TOP 1 Sample_Number As MaxSampleNumberThatOccursTwice
FROM dbo.TableName
GROUP BY Sample_Number
HAVING COUNT(*) = 2
ORDER BY Sample_Number DESC

Answer 3

;with cte
as
(select sample_number
from #temp
group by Sample_Number 
having
count(Analysis_ID)=2
)
select max(sample_number) from cte

Answer 4

我会使用subselect：

SELECT MAX (sample_number) 
FROM  (SELECT sample_number
        FROM TAB1
        GROUP BY sample_number
        HAVING COUNT(sample_number) =2 
        )

Answer 5

按Sample_Number分组并获取组的计数并且只选择计数是否为2

select Sample_Number, count(*) count from someTable
group by Sample_Number
having count=2

如何选择出现2次的最大值？

5 个答案: