SQL Server DATEDIFF 行间计算列 [英] SQL Server DATEDIFF Computed Column Between Rows
问题描述
我目前有一个类似的表 -
I currently have a table similar to this -
RecordTime Running Fault
-----------------------------------------------
2016-09-15 11:32:01.00 0 202
2016-09-15 11:32:08.00 1 202
2016-09-15 11:39:31.00 0 21
2016-09-15 11:40:07.00 1 4
2016-09-15 11:42:11.00 0 21
2016-09-15 11:42:39.00 1 45
然后我想计算每条记录的 RecordTimes 之间的时间差.为此,我使用以下 -
I then wanted to calculate the time difference between the RecordTimes for each record. For this I am using the following -
WITH rows AS
(
SELECT *, ROW_NUMBER() OVER (ORDER BY RecordTime) AS rn
FROM dbo.Table1
)
SELECT DATEDIFF(second, mc.RecordTime, mp.RecordTime)
FROM rows mc
JOIN rows mp
ON mc.rn = mp.rn - 1
哪个返回 -
(No column name)
----------------
7
443
36
124
28
303
不过,我真正想做的是在原始表中创建一个计算列,为我提供这些值.这可能吗?
What I actually want to do, though, is create a computed column in the original table that gives me these values. Is this possible?
我认为我可以将查询转换为 UDF,然后在列中引用它,但我对这种工作的经验不是很丰富.
I thought that I might be able to convert the query into a UDF and then reference that in the column, but I'm not very experienced with that kind of work.
---编辑---
最终结果应该是 -
RecordTime Running Fault Diff
--------------------------------------------------------
2016-09-15 11:32:01.00 0 202 7
2016-09-15 11:32:08.00 1 202 443
2016-09-15 11:39:31.00 0 21 36
2016-09-15 11:40:07.00 1 4 124
2016-09-15 11:42:11.00 0 21 28
2016-09-15 11:42:39.00 1 45 303
推荐答案
我建议您为此目的使用视图:
I recommend you to use a view for this purpose:
CREATE VIEW Table1_vw
AS
WITH cte AS (
SELECT *,
ROW_NUMBER() OVER (ORDER BY RecordTime) AS rn
FROM dbo.Table1
)
SELECT mc.RecordTime,
mc.Running,
mc.Fault,
DATEDIFF(second, mc.RecordTime, mp.RecordTime) Diff
FROM cte mc
LEFT JOIN cte mp
ON mc.rn = mp.rn - 1
由于您使用的是 SQL Server 2012,您可以使用 LEAD 功能:
Since you are using SQL Server 2012 you can use LEAD function:
CREATE VIEW Table1_vw
AS
SELECT RecordTime,
Running,
Fault,
DATEDIFF(second,RecordTime,LEAD(RecordTime,1,NULL) OVER (ORDER BY RecordTime ASC) ) as Diff
FROM Table1
GO
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