How do I exclude rows when an incremental value starts over? - sql-server

Question

I am a newbie poster but have spent a lot of time researching answers here. I can't quite figure out how to create a SQL result set using SQL Server 2008 R2 that should probably be using lead/lag from more modern versions. I am trying to aggregate data based on sequencing of one column, but there can be varying numbers of instances in each sequence. The only way I know a sequence has ended is when the next row has a lower sequence number. So it may go 1-2, 1-2-3-4, 1-2-3, and I have to figure out how to make 3 aggregates out of that.
Source data is joined tables that look like this (please help me format):
recordID instanceDate moduleID iResult interactionNum
1356 10/6/15 16:14 1 68 1
1357 10/7/15 16:22 1 100 2
1434 10/9/15 16:58 1 52 1
1435 10/11/15 17:00 1 60 2
1436 10/15/15 16:57 1 100 3
1437 10/15/15 16:59 1 100 4
I need to find a way to separate the first 2 rows from the last 4 rows in this example, based on values in the last column.
What I would love to ultimately get is a result set that looks like this, which averages the iResult column based on the grouping and takes the first instanceDate from the grouping:
instanceDate moduleID iResult
10/6/15 1 84
10/9/15 1 78
I can aggregate to get this result using MIN and AVG if I can just find a way to separate the groups. The data is ordered by instanceDate (please ignore the date formatting here) then interactionNum and the group separation should happen when the query finds a row where the interactionNum is <= than the previous row (will usually start over with '1' but not always, so prefer just to separate on a lower or equal integer value).
Here is the query I have so far (includes the joins that give the above data set):
SELECT
X.*
FROM
(SELECT TOP 100 PERCENT
instanceDate, b.ModuleID, iResult, b.interactionNum
FROM
(firstTable a
INNER JOIN
secondTable b ON b.someID = a.someID)
WHERE
a.someID = 2
AND b.otherID LIKE 'xyz'
AND a.ModuleID = 1
ORDER BY
instanceDate) AS X
OUTER APPLY
(SELECT TOP 1
*
FROM
(SELECT
instanceDate, d.ModuleID, iResult, d.interactionNum
FROM
(firstTable c
INNER JOIN
secondTable d ON d.someID = c.someID)
WHERE
c.someID = 2
AND d.otherID LIKE 'xyz'
AND c.ModuleID = 1
AND d.interactionNum = X.interactionNum
AND c.instanceDate < X.instanceDate) X2
ORDER BY
instanceDate DESC) Y
WHERE
NOT EXISTS (SELECT Y.interactionNum INTERSECT SELECT X.interactionNum)
But this is returning an interim result set like this:
instanceDate ModuleID iResult interactionNum
10/6/15 16:10 1 68 1
10/6/15 16:14 1 100 2
10/15/15 16:57 1 100 3
10/15/15 16:59 1 100 4
and the problem is that interactionNum 3, 4 do not belong in this result set. They would go in the next result set when I loop over this query. How do I keep them out of the result set in this iteration? I need the result set from this query to just include the first two rows, 'seeing' that row 3 of the source data has a lower value for interactionNum than row 2 has.

Answer 1

Not sure what ModuleID was supposed to be used, but I guess you're looking for something like this:
select min (instanceDate), [moduleID], avg([iResult])
from (
select *,row_number() over (partition by [moduleID] order by instanceDate) as RN
from Table1
) X
group by [moduleID], RN - [interactionNum]
The idea here is to create a running number with row_number for each moduleid, and then use the difference between that and InteractionNum as grouping criteria.
Example in SQL Fiddle

Answer 2

Here is my solution, although it should be said, I think #JamesZ answer is cleaner.
I created a new field called newinstance which is 1 wherever your instanceNumber is 1. I then created a rolling sum(newinstance) called rollinginstance to group on.
Change the last select to SELECT * FROM cte2 to show all the fields I added.
IF OBJECT_ID('tempdb..#tmpData') IS NOT NULL
DROP TABLE #tmpData
CREATE TABLE #tmpData (recordID INT, instanceDate DATETIME, moduleID INT, iResult INT, interactionNum INT)
INSERT INTO #tmpData
SELECT 1356,'10/6/15 16:14',1,68,1 UNION
SELECT 1357,'10/7/15 16:22',1,100,2 UNION
SELECT 1434,'10/9/15 16:58',1,52,1 UNION
SELECT 1435,'10/11/15 17:00',1,60,2 UNION
SELECT 1436,'10/15/15 16:57',1,100,3 UNION
SELECT 1437,'10/15/15 16:59',1,100,4
;WITH cte1 AS
(
SELECT *,
CASE WHEN interactionNum=1 THEN 1 ELSE 0 END AS newinstance,
ROW_NUMBER() OVER(ORDER BY recordID) as rowid
FROM #tmpData
), cte2 AS
(
SELECT *,
(select SUM(newinstance) from cte1 b where b.rowid<=a.rowid) as rollinginstance
FROM cte1 a
)
SELECT MIN(instanceDate) AS instanceDate, moduleID, AVG(iResult) AS iResult
FROM cte2
GROUP BY moduleID, rollinginstance