從一系列日期開始的持續時間 - sql-server

Question

使用SQL Server 2012.每天晚上，數據倉庫負載會填充貸款經歷的里程碑日期表。數據如下所示：

CREATE TABLE TestData (LoanKey int, MilestoneCompletedDate datetime, Duration int) 

INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-16 16:51:56.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-18 15:11:29.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-23 16:21:59.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-28 14:52:00.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-08-26 10:53:37.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-09-19 15:16:38.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-09-20 08:31:38.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-08 15:56:05.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-16 16:11:10.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-10-09 11:20:35.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (2, '2013-09-10 11:15:09.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-06-03 16:22:32.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-06-21 14:46:24.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-08-30 10:03:08.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-08-30 13:55:17.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-09-03 15:28:22.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-09-04 09:30:08.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-09-12 10:44:46.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-09-25 16:06:43.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-06-24 11:59:25.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-09-25 16:06:43.000') 
INSERT TestData (LoanKey, MilestoneCompletedDate) VALUES (42, '2013-01-17 15:06:14.000') 

數據加載後，我想更新「持續時間」字段。下面是一些僞代碼：

UPDATE TestData SET Duration = 'Find the DateDiff between the current rows MilestoneCompletedDate and the next greatest milestone completion date for the same loan' 

我可以生成與PARTITION BY和ORDER BY行號：

SELECT 
    LoanKey, 
    MilestoneCompletedDate, 
    ROW_NUMBER() OVER (PARTITION BY LoanKey ORDER BY MilestoneCompletedDate DESC) AS SequenceNumber 
FROM 
    [dbo].[TestData] 

在哪裏何去何從填充時段的任何想法？

謝謝你看！

Answer 1

既然你的SQL Server 2012上，您可以使用LEAD：在SQL Server

從相同的結果一行後續不使用的訪問設置數據自2012年加盟提供LEAD訪問當前行之後的給定物理偏移處的行。

;With leads as (
    select *, LEAD(MilestoneCompletedDate) OVER 
       (PARTITION BY LoanKey 
        ORDER BY MilestoneCompletedDate) as NextCompletion 
    from TestData 
) 
UPDATE leads SET Duration =DATEDIFF(second,MilestoneCompletedDate,NextCompletion) 

select * from TestData 

產地：

LoanKey  MilestoneCompletedDate Duration 
----------- ----------------------- ----------- 
2   2013-10-16 16:51:56.000 166773 
2   2013-10-18 15:11:29.000 436230 
2   2013-10-23 16:21:59.000 426601 
2   2013-10-28 14:52:00.000 NULL 
2   2013-08-26 10:53:37.000 1297292 
2   2013-09-19 15:16:38.000 62100 
2   2013-09-20 08:31:38.000 1581867 
2   2013-10-08 15:56:05.000 69870 
2   2013-10-16 16:11:10.000 2446 
2   2013-10-09 11:20:35.000 622235 
2   2013-09-10 11:15:09.000 792089 
42   2013-06-03 16:22:32.000 1549432 
42   2013-06-21 14:46:24.000 249181 
42   2013-08-30 10:03:08.000 13929 
42   2013-08-30 13:55:17.000 351185 
42   2013-09-03 15:28:22.000 64906 
42   2013-09-04 09:30:08.000 695678 
42   2013-09-12 10:44:46.000 1142517 
42   2013-09-25 16:06:43.000 0 
42   2013-06-24 11:59:25.000 5781823 
42   2013-09-25 16:06:43.000 NULL 
42   2013-01-17 15:06:14.000 11841378 

---

在SQL Server的早期版本，我會考慮你的ROW_NUMBER()基於查詢並做了一些自加入該被提及的LEAD文檔：

;With Ordered as (
    SELECT 
     LoanKey, 
     MilestoneCompletedDate, 
     ROW_NUMBER() OVER (PARTITION BY LoanKey 
       ORDER BY MilestoneCompletedDate DESC) AS SequenceNumber 
    FROM 
     [dbo].[TestData] 
) 
UPDATE o1 SET Duration = 
    DATEDIFF(second,o1.MilestoneCompletedDate,o2.MilestoneCompletedDate) 
FROM Ordered o1 
LEFT JOIN Ordered o2 
ON o1.LoanKey = o2.LoanKey and o1.SequenceNumber = o2.SequenceNumber - 1 

Answer 2

這應該做的工作，改變HOUR到你喜歡的任何單位：

UPDATE a 
SET Duration = DATEDIFF(HOUR 
         ,(SELECT MAX(b.MilestoneCompletedDate) 
          FROM TestData b 
          WHERE b.MilestoneCompletedDate < a.MilestoneCompletedDate 
          AND b.LoanKey = a.LoanKey) 
         ,a.MilestoneCompletedDate) 
FROM TestData a 
WHERE Duration IS NULL 

SQLFiddle似乎在此刻SQL服務器被打破，所以不能發佈小提琴，但前4行（通過LoadKey, MilestoneCompletedDate訂購）更新後的問世：

LoanKey MilestoneCompletedDate Duration 
2  2013-08-26 10:53:37.000 NULL 
2  2013-09-10 11:15:09.000 361 
2  2013-09-19 15:16:38.000 220 
2  2013-09-20 08:31:38.000 17 

或者，你可以使用ROW_NUMBER像自己所想的，但它是一個有些凌亂。例如：

;WITH cte AS (
    SELECT 
     LoanKey, 
     MilestoneCompletedDate, 
     Duration, 
     ROW_NUMBER() OVER (PARTITION BY LoanKey 
          ORDER BY MilestoneCompletedDate ASC) AS SeqNum 
    FROM @TestData 
    WHERE duration IS NULL 
) 
UPDATE a 
SET Duration = DATEDIFF(HOUR 
         ,b.MilestoneCompletedDate 
         ,a.MilestoneCompletedDate) 
FROM cte a 
INNER JOIN cte b ON a.LoanKey = b.LoanKey 
       AND a.SeqNum = b.SeqNum + 1 

它返回相同的結果集。