如何计算两个日期之间的天数以及多个日期的总天数

Question

我需要创建一个查询来计算已清除日期和未清除日期之间的天数，然后计算这些天数的总数。

以下是数据集的示例：

 Name         Status         Date      Explanation
Tony Camp    Uncleared       9/4/17    Need more information.
Tony Camp    Cleared         9/7/17    Paper work signed
Tony Camp    Uncleared       9/9/17    Placement is full. 
Tony Camp    Cleared         9/25/17   Placement is ready.
Everly Mo    Uncleared       9/26/17   Not ready. 
Everly Mo    Cleared         10/01/17  Ready.
Stan Mann    Uncleared       10/01/17  Not Ready.

以下是该报告的示例：

Case        Person         Number of Uncleared Days
12          Tony Camp             18
25          Everly Mo             4

我通过计算每个未清除状态和已清除状态之间的天数，然后将天数相加得出结果。 这将为我提供每个人每个未清算和清算日期之间的总天数。

经验。 我得到了 9/4/17 和 9/7/17 之间的差异，然后是 9/9/17 和 9/25/17 之间的差异。 然后我添加了天数以获得未清除天数的总数。

Answer 1

你可以用这个。

;WITH CTE AS 
(
    SELECT *, 
    RN = ROW_NUMBER() OVER (PARTITION BY Name, Status ORDER BY [Date]) 
    FROM DataSet
)
SELECT 
    T1.Name Person,  
    SUM(DATEDIFF(DAY,T1.Date, T2.Date)) -1 [Number of Uncleared Days] 
FROM CTE T1 INNER JOIN CTE T2 ON T1.Name = T2.Name AND T2.Status ='Cleared' AND T1.RN = T2.RN 
WHERE T1.Status ='Uncleared'
GROUP BY T1.Name

对于 SQL2000：

SELECT Person, SUM([Date_Diff]) - 1 AS [Number of Uncleared Days]  FROM
( 
    SELECT 
        D1.Name AS Person, 
        DATEDIFF(DAY, [Date] , 
            (SELECT TOP 1 [Date] 
            FROM DataSet D2 
            WHERE D2.Status ='Cleared' 
                AND D1.Name = D2.Name 
                AND D1.Date < D2.Date) ) AS [Date_Diff] 
    FROM 
        DataSet AS D1
    WHERE 
        D1.Status ='Uncleared'
) AS SubQ
WHERE 
    [Date_Diff] IS NOT NULL
GROUP BY Person