Question

使用SQL Server 2012.每晚数据仓库负载都会填充贷款通过的里程碑日期表。数据如下所示：

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')

加载数据后，我想更新“持续时间”字段。这是一些伪代码：

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

我可以使用PARTITION BY和ORDER BY生成行号：

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

有关从何处开始填充持续时间的任何想法？

谢谢你的期待！

Answer 1

这应该可以完成工作，将HOUR更改为您喜欢的任何单位：

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目前似乎已被打破，因此无法发布小提琴，但更新后排名前4行（按LoadKey, MilestoneCompletedDate排序）为：

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，你可以像你想的那样使用ROW_NUMBER，但它有点混乱。类似的东西：

;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

返回相同的结果集。

Answer 2

由于您使用的是SQL Server 2012，因此可以使用LEAD：

在SQL Server 2012中不使用自联接访问同一结果集中后续行的数据。LEAD提供对当前行之后的给定物理偏移量的行的访问。

;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

产地：

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

在以前版本的SQL Server上，我已经采用了基于ROW_NUMBER()的查询，并完成了LEAD文档中引用的自联接：

;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

一系列日期的持续时间 - sql-server

2 个答案: