Transaction data aggregate - sql-server

Question

As a disclaimer, I am not entirely sure the title of the question is best, if not I apologize.
I am trying to calculate cycle times for individuals, but files are occasionally transferred out of their work queues and eventually back. There are no unique transaction IDs recorded just a date and time stamp.
I tried looking for an aggregate group by functions and was told that is not a feature sql-server has.
I started by trying to identify the first and last transaction and was going to build out the query from there but it wasn't too helpful. Any insight would be very helpful.
Changedate is when the transfer from one person to another is recorded (year, moth, day time)
select a.claimId,
a.claimincidentID,
cast(a.changeDate as date) changedate,
a.claimNum,
a.Coverage,
a.AssignedAdjID,
a.AssignedAdj,
a.AssignedUnit,
a.TransferedAdjID,
a.TransferedAdj,
a.TransferedUnit,
a.usertypeid,
a.ChangedBy,
b.Feature_Create_Date,
DATEDIFF(day, b.Feature_Create_Date, a.changedate) transfer1,
cast(FIRST_VALUE(changeDate) OVER (ORDER BY changedate ASC)as date) AS firstchangedate,
cast(LAST_VALUE(changeDate) OVER (ORDER BY a.changedate ASC)as date) AS lastchangedate
from DB1.dbo.Assign_Transfer a
left join DB2.claimslist b on a.claimid=b.claimId
group by a.claimId, a.claimincidentID, a.changeDate, a.claimNum, a.Coverage, a.AssignedAdjID, a.AssignedAdj, a.AssignedUnit, a.TransferedAdjID, a.TransferedAdj, a.TransferedUnit, a.usertypeid, a.ChangedBy, b.Feature_Create_Date

Answer 1

Think of each of these rows as a Start (because the most recent one hasn't ended)
We would need to generate the complement End for this person in the chain.
Then with pairs of Start/End one could create GrossDuration.
Even after we get an assignment's start and end date/time,
we will have workday (8-4, or 9-5, or noon-8, ...) considerations,
also Sat/Sun/Hol and Vacation/out-of-office.
All of which affect Duration--- For Each Person differently.
Which would need to be factored by workday/etc into AdjDuration.
Lets say we can sequence these
Row_Number() Over (Partition by claimID Order by changeDate) as tfrNum
Assigned is the prior, and Transfered is the next
1, 2, 3, ... thru N
V
a.changeDate -- NOW()
V V
a.AssignedAdjID, | a.TransferedAdjID,
a.AssignedAdj, | a.TransferedAdj,
a.AssignedUnit, | a.TransferedUnit,
|
a.usertypeid,
a.ChangedBy,
So, is tfrNum=1 or tfrNum=N the oddball??
Lets look at pairs: each pair goes StartFrom->EndTo
1-2, 2-3, 3-4, 4-5, 5-6, 6-Now
----
From row1 we get TransferredID Start(changeDate) and
from row2 we get AssignedAdjID End (changeDate)
-- 2-3, 3-4, 4-5, etc repeating
--except for
From row6 we get TransferredID Start(changeDate) and
from default (still them) End (Now)
-- -- except again when TransferredUnit is "Closed"
After getting these pairs and their Start and End, we can do the Duration calc.
I need to visualize this problem before I try to run some sql. Real data would help.
Lets start with this, and later I would expand on it after you get it working and look at some data--
With cte_tfrNum (claimID, changeDate, tfrNum, tfrMax) AS
(
SELECT
a.claimId
,a.changeDate
,ROW_NUMBER() Over ( Partition By a.claimId Order By a.changeDate) as tfrNum
,b.tfrMax
FROM DB1.dbo.Assign_Transfer a
-- just for giggles, lets also get the max# of transfers for this claim
Left Join
(SELECT claimId, COUNT(*) as tfrMax
FROM DB1.dbo.Assign_Transfer
Group By claimId
) as b
On b.claimId = a.claimId
)
-- Statement using the CTE
Select
tfrTo.*
From cte_tfrNum as tfrTo

Answer 2

Thank you! I was able to take what you gave me and add a few things to be able to look at what I needed.
select
case when abc.tfrMax > abc.tfrnum then datediff(day,lag(abc.changedate) over(partition by abc.claimID order by abc.claimId),abc.changeDate)
when abc.tfrMax = abc.tfrnum then datediff(day,lag(abc.changedate) over(partition by abc.claimID order by abc.claimId),abc.changeDate)
end as test
, abc.*
from
(
SELECT
a.claimId
,a.changeDate
,a.AssignedAdj
,a.TransferedAdj
,a.Coverage
,ROW_NUMBER() Over ( Partition By a.claimId Order By a.changeDate) as tfrNum
,b.tfrMax
FROM db1.dbo.Assign_Transfer a
Left Join
(SELECT claimId, COUNT(*) as tfrMax
FROM db1.dbo.Assign_Transfer
Group By claimId
) as b
On b.claimId = a.claimId
) abc
group by
abc.claimId
,abc.changeDate
,abc.AssignedAdj
,abc.TransferedAdj
,abc.Coverage
,abc.tfrMax
,abc.tfrNum