Question

我正在尝试选择不同的DP，RN并从结果中选择仅在表'EDate'=值中的另一个col的结果，然后在此之后获得行数。这是我到目前为止，但它不起作用..

SELECT 
    COUNT(*) AS eCount 
FROM 
    (SELECT * 
     FROM
         (SELECT DISTINCT
              DP, RN
          FROM 
              ECount 
          WHERE
              DType = 'STRUCT')
     WHERE
         Month(EDate) = '07')) AS rows

如果建议我这样做，我无法将EDate添加到Select Distinct，因为我不希望这会弄乱我的不同选择。

例如

DP      RN      Edate    
DP01    RN01    21/06/2017    
DP01    RN01    22/07/2017  
DP02    RN03    22/07/2017   yes 
DP02    RN03    22/07/2017    
DP01    RN04    22/07/2017   yes
DP02    RN05    22/07/2017   yes
DP03    RN06    22/07/2017   yes

结果应= 4

Answer 1

您不能在外部查询中使用WHERE Month(EDate) = '07'，因为EDate不是内部查询的一部分。

尝试使用少一个派生表：

SELECT COUNT(*)
FROM
(
    SELECT DISTINCT DP, RN
    FROM ECount t0
    WHERE DType = 'STRUCT'
    AND Month(EDate) = 7
    AND NOT EXISTS
    (
        SELECT 1
        FROM ECount t1
        WHERE t1.DP = t0.DP
        AND t1.RN = t0.RN
        AND t1.Month(EDate) <> 7
        AND t1.DType = 'STRUCT' -- Not sure about this condition
    )
) As rows

Answer 2

;With Cte
As
(
    Select 
        DP,
        RN,
        EDate,
        Row_Number() Over(Partition By DP Order By RN Desc) As RowNum 
    From Example
    Where Month(EDate) = 07
)
Select 
    DP, 
    RN, 
    EDate
From Cte
Where RowNum = 1
Order By DP;

Sql选择不同的行计数

2 个答案: