SQL Server :Substracting 2nd row from 1st ,3rd row from 2nd etc - sql-server

Question

I'm struggling with an algorithm in SQL server , and I have no clue how to solve this .
I have a column with timestamps on which I've ordered by desc .
I need to find out the differences between de 2nd row and the 1st , the 3rd row and the 2 nd as so on and display this in a new row .The final table should look like this :
ID Type Time_Stamp Difference
xxx YYY 00:03:12 00:00:02
xxx ZZZ 00:03:14 00:00:02
xxx ZZZ 00:03:16
Can I use some kind of SQL function ? Please let me know if you have any ideas .
Cheers ,

Answer 1

Use Window Function
;WITH cte
AS (SELECT Row_number()
OVER(
ORDER BY time_stamp) rn,
*
FROM yourtable)
SELECT a.ID,
a.Type,
a.Time_Stamp,
CONVERT(VARCHAR(10), Datediff(second, a.Time_Stamp, b.Time_Stamp)/3600)
+ ':'
+ RIGHT('00'+CONVERT(VARCHAR(2), (Datediff(second, a.Time_Stamp, b.Time_Stamp)%3600)/60), 2)
+ ':'
+ RIGHT('00'+CONVERT(VARCHAR(2), Datediff(second, a.Time_Stamp, b.Time_Stamp)%60), 2) AS [Difference]
FROM cte a
LEFT JOIN cte b
ON a.rn = b.rn - 1
If you are using Sql Server 2012+ then use Lead Function
;WITH cte
AS (SELECT *,
Datediff(second, time_stamp, Lead(time_stamp)
OVER(
ORDER BY time_stamp)) AS Sec
FROM yourtable)
SELECT a.ID,
a.Type,
a.Time_Stamp,
CONVERT(VARCHAR(10), sec/3600) + ':'
+ RIGHT('00'+CONVERT(VARCHAR(2), (sec%3600)/60), 2)
+ ':'
+ RIGHT('00'+CONVERT(VARCHAR(2), sec%60), 2) AS [Difference]
FROM cte a
Update : To insert into temp table do this.
;WITH cte
AS (SELECT Row_number()
OVER(
ORDER BY time_stamp) rn,
*
FROM yourtable)
SELECT a.ID,
a.Type,
a.Time_Stamp,
CONVERT(VARCHAR(10), Datediff(second, a.Time_Stamp, b.Time_Stamp)/3600)
+ ':'
+ RIGHT('00'+CONVERT(VARCHAR(2), (Datediff(second, a.Time_Stamp, b.Time_Stamp)%3600)/60), 2)
+ ':'
+ RIGHT('00'+CONVERT(VARCHAR(2), Datediff(second, a.Time_Stamp, b.Time_Stamp)%60), 2) AS [Difference]
into #tempTable --Here you need to use into temptable
FROM cte a
LEFT JOIN cte b
ON a.rn = b.rn - 1
or create the temp table and use
......
Insert into #temptable
SELECT a.ID,
a.Type,
a.Time_Stamp
......

Answer 2

SAMPLE TABLE
CREATE TABLE #TEMP(ID VARCHAR(10),[TYPE] VARCHAR(10),TIME_STAMP TIME)
INSERT INTO #TEMP
SELECT 'xxx' , 'YYY', '00:03:12'
UNION ALL
SELECT 'xxx', 'ZZZ', '00:03:14'
UNION ALL
SELECT 'xxx', 'ZZZ', '00:03:16'
You need to do self join logic to get next row's record
QUERY
;WITH CTE AS
(
SELECT ROW_NUMBER()OVER(ORDER BY TIME_STAMP)RNO,*
FROM #TEMP
)
SELECT C1.*,'00:00:'+CAST(DATEDIFF(S,C1.TIME_STAMP,C2.TIME_STAMP)AS VARCHAR(2)) D
FROM CTE C1
LEFT JOIN CTE C2 ON C1.RNO=C2.RNO-1
Click here to view result