SQL Server Difference of Aggregate Window - sql

Question

I want to fetch some data from an SQL Server table by creating windows of 15 mins from the start time and find the difference between the MAX and MIN of a certain column (value) in these windows.
The SQL Table stores some telemetry data captured every minute.
Are there any T-SQL functionalities that I can utilize to get such output without running a loop (Windowed Aggregation sort, etc.)?
I could implement this using a loop, but this is very slow as it would take data from every window and add it to a temp table. Below is a dumbed-down snippet of the code:
WHILE(#startTime <#endTimeInput)
BEGIN
INSERT INTO #energyDataTable
SELECT MIN(timeStamp) as startTime, MAX(timeStamp) as endTime, ROUND(MAX (value) - MIN (value),2) as value
FROM PLANT1.DATA_TABLE as ts
WHERE ts.unixTimestamp>=#startTime and ts.unixTimestamp<= #endTime
GROUP BY ts.logicalId
--Increment startTime and endTime to goto next window
SET #startTime = #endTime;
SET #endTime = #startTime + 15 * 60000; --converting 15 mins to millisecs
END
Timestamp
value
unixTime
2021-11-08 00:00:09.000
1527.6
1636329609000
2021-11-08 00:01:09.000
1528.1
1636329669000
2021-11-08 00:02:09.000
1528.6
1636329729000
....
....
....
2021-11-08 00:13:09.000
1534.5
1636330389000
2021-11-08 00:14:09.000
1535.3
1636330479000
2021-11-08 00:15:09.000
1535.5
1636330509000
2021-11-08 00:16:09.000
1536.0
1636330569000
2021-11-08 00:17:09.000
1528.6
1636330629000
....
....
....
2021-11-08 00:28:09.000
1542.5
1636331289000
2021-11-08 00:29:09.000
1543.3
1636331379000
Needs to be transformed to (I don't necessarily need end_time: Added for better understanding):
start_time
end_time
value
2021-11-08 00:00:09.000
2021-11-08 00:14:39.000
7.7
2021-11-08 00:15:09.000
2021-11-08 00:29:39.000
7.8

Answer 1

update
the solution is to get first and last row from 15 mins sections
it can be done like this:
create table #t
(
ts datetime2
,val dec(9,2)
)
insert into #t
values
('2021-11-08 00:00:09.000', 1527.6)
,('2021-11-08 00:01:09.000', 1528.1)
,('2021-11-08 00:02:09.000', 1528.6)
,('2021-11-08 00:13:09.000', 1534.5)
,('2021-11-08 00:14:09.000', 1535.3)
,('2021-11-08 00:15:09.000', 1535.5)
,('2021-11-08 00:16:09.000', 1536.0)
,('2021-11-08 00:17:09.000', 1528.6)
,('2021-11-08 00:28:09.000', 1542.5)
,('2021-11-08 00:29:09.000', 1543.3)
;with
cte_partitions as
(
select *
from
(
select *
,row_number() over(partition by M15.[partition] order by T.ts) as row_asc_id -- first row
,row_number() over(partition by M15.[partition] order by T.ts desc) as row_desc_id -- last row
from #t T
outer apply
(
-- 15 minutes partitions = hours + minutes / 15
select format(ts, 'yyyyMMddHH') + cast(datepart(minute, ts) / 15 as char(1)) as [partition]
) M15
) T
where T.row_asc_id = 1
or T.row_desc_id = 1
)
select PF.ts
,PL.val - PF.val
from cte_partitions PF
inner join cte_partitions PL
on PF.[partition] = pl.[partition]
where PF.row_asc_id = 1
and PL.row_desc_id = 1
Although it's fully inline with your example, it will work only if you have every minute without seconds and so on and so forth.
take a look, please
create table #t
(
ts datetime2
,val int
)
insert into #t
values
('2021-11-09T01:01:00.000Z', 100)
,('2021-11-09T01:02:00.000Z', 102)
,('2021-11-09T01:03:00.000Z', 103)
,('2021-11-09T01:04:00.000Z', 105)
,('2021-11-09T01:05:00.000Z', 107)
,('2021-11-09T01:06:00.000Z', 108)
,('2021-11-09T01:07:00.000Z', 120)
,('2021-11-09T01:08:00.000Z', 123)
,('2021-11-09T01:09:00.000Z', 128)
,('2021-11-09T01:10:00.000Z', 135)
select format(ts, 'hh:mm:ss') + ' - ' + format(next_ts, 'hh:mm:ss')
,cast(next_val - val as varchar(10)) + ' (' + cast(next_val as varchar(10)) + ' - ' + cast(val as varchar(10)) + ')'
from
(
select ts
,val
,lead(ts) over(order by ts) as next_ts
,lead(val) over(order by ts) as next_val
from
(
select *, (row_number() over(order by ts) - 1) % 4 as row_id
from #t
) SQ
where row_id = 0
) SQ
where next_ts is not null

Answer 2

To aggregate them in windows of 5 minutes?
Then this may be as simple as also grouping by the minutes divided by 12.
SELECT
CONCAT(CONVERT(VARCHAR, MIN(t.[Timestamp]), 108), ' - ', CONVERT(VARCHAR, MAX(t.[Timestamp]), 108)) AS Agg_Timestamp,
CONCAT(MAX(t.Energy_Value)-MIN(t.Energy_Value), ' (', MAX(t.Energy_Value), '-', MIN(t.Energy_Value), ')' ) AS Agg_Energy_Value
FROM yourtable t
GROUP BY CAST(t.[Timestamp] AS DATE),
DATEPART(hour, t.[Timestamp]),
ROUND((DATEPART(minute, t.[Timestamp])/12.0), 0)
Result:
Agg_Timestamp | Agg_Energy_Value
:------------------ | :---------------
01:01:00 - 01:05:00 | 7 (107-100)
01:06:00 - 01:10:00 | 27 (135-108)