Previous Record With Cross Apply Syntax - sql

Question

I have a table called ArchiveActivityDetails which shows the history of a Customer Repair Order. 1 Repair Order will have many visits (ActivityID) with a Technician allocated depending on who is available for that planned visit.
The system automatically allocates the time that is required for a job but sometimes a job requires longer so we manually ammend jobs.
My initial query from the customer was to pull the manually ammended jobs (ie: jobs where PlannedDuration >=60 minutes) and shows the Technician linked to that manually ammended job.
This report works fine.
My most recent request from the customer is to now ADD a column showing WHO WAS THE PREVIOUS TECHNICIAN linked that the Repair Order.
My collegues suggested I do a Cross Apply going back to the ArchiveActivityDetails table and then show "Previous Tech" but I have not used Cross Apply before and I am struggling with the syntax and unable to get the results I want. In my Cross Apply I used LAG to work out the 'PrevTech' but when pulling it into my main report, I get NULL. So I assume I am not doing the Cross Apply correctly.
DECLARE #DateFrom as DATE = '2019-05-20'
DECLARE #DATETO AS DATE = '2019-07-23'
----------------------------------------------------------------------------------
SELECT
AAD.Date
,ASM.ASM
,A.ASM as PrevASM
,ASM.KDGID2
,R.ResourceName
,R.ID_ResourceID
,A.ServiceOrderNumber
,CONCAT(EN.TECHVORNAME, ' ' , EN.TECHNACHNAME) as TechName
,A.PrevTech
,EN.TechnicianID
,AAD.ID_ActivityID
,SO.ServiceOrderNumber
,AAD.VisitNumber
,AAD.PlannedDuration
,AAD.ActualDuration
,AAD.PlannedDuration-AAD.ActualDuration as DIFF
,DR.Original_Duration
FROM
[Easy].[ASMTrans] AS ASM
INNER JOIN
[FS_OTBE].[EngPayrollNumbers] AS EN
ON ASM.KDGID2 = EN.KDGID2
INNER JOIN
[OFSA].[ResourceID] AS R
ON EN.TechnicianID = Try_cast(R.ResourceName as int)
INNER JOIN
[OFSDA].[ArchiveActivityDetails] as [AAD]
ON R.[ID_ResourceID] = AAD.ID_ResourceID
INNER JOIN
[OFSA].[ServiceOrderNumber] SO
ON SO.ID_ServiceOrderNumber = AAD.ID_ServiceOrderNumber
LEFT JOIN
[OFSE].[DurationRevision] DR
on DR.ID_ActivityID = AAD.ID_ActivityID
CROSS APPLY
(
SELECT
AD.Date
,AD.ID_CountryCode
,AD.ID_Status
,Activity_TypeID
,AD.ID_ActivityID
,AD.ID_ResourceID
,SO.ServiceOrderNumber
,ASM.ASM
,LAG(EN.TECHVORNAME+ ' '+EN.TECHNACHNAME) OVER (ORDER BY SO.ServiceOrderNumber,AD.ID_ActivityID) as PrevTech
,AD.VisitNumber
,AD.ID_ServiceOrderNumber
,AD.PlannedDuration
,AD.ActualDuration
,ROW_NUMBER() OVER (PARTITION BY AD.ID_ServiceOrderNumber Order by AD.ID_ActivityID,AD.Date) as ROWNUM
FROM
[Easy].[ASMTrans] AS ASM
INNER JOIN
[FS_OTBE].[EngPayrollNumbers] AS EN
ON ASM.KDGID2 = EN.KDGID2
INNER JOIN
[OFSA].[ResourceID] AS R
ON EN.TechnicianID = Try_cast(R.ResourceName as int)
INNER JOIN
[OFSDA].[ArchiveActivityDetails] as [AD]
ON R.[ID_ResourceID] = AD.ID_ResourceID
INNER JOIN
[OFSA].[ServiceOrderNumber] SO
ON SO.ID_ServiceOrderNumber = AD.ID_ServiceOrderNumber
WHERE
AAD.ID_ActivityID = AD.ID_ActivityID
AND
AD.ID_CountryCode = AAD.ID_CountryCode
AND AD.ID_Status = AAD.ID_Status
AND AD.ID_ResourceID = AAD.ID_ResourceID
AND AD.Activity_TypeID = AAD.Activity_TypeID
AND AD.ID_ServiceOrderNumber = AAD.ID_ServiceOrderNumber
AND AD.Date >= '2019-05-01'
) as A
WHERE
ASM.KDGID2
IN (50008323,50008326,50008329,50008332,50008335,50008338,50008341,50008344,50008347,50008350,50008353,50008356,50008359,50008362,50008365)
AND AAD.ID_Status = 1
AND AAD.ID_CountryCode = 7
AND AAD.Activity_TypeID=91
AND
(
AAD.[Date] BETWEEN IIF(#DateFrom < '20190520','20190520',#DateFrom) AND IIF(#DateTo < '20190520','20190520',#DateTo))
AND AAD.ActualDuration > 11
AND
(
(DR.Original_Duration >= 60)
OR
(DR.ID_ActivityID IS NULL AND AAD.PlannedDuration >= 60))
I expect to see the previous Tech and previous Area Sales Manager for the job that was Manually Ammended.
Business Reason: Managers want to see who initially requested for the job to be Manually Ammended. The time requested is being over estimated which is wasting time. To plan better they need to see who requests extra time at a job and try to reduce the time.
I will attach the ArchiveActivityDetail table showing the history of a Repair Order as well as expected results.

Answer 1

Your query results in the cross apply will appear as a table in your query, so you can use top(1) and order by descending to get the first row ordered by what you want (it looks like ActivityId? maybe VisitNumber?).
Simplifying to get at the root of the issue, say you have just one table with ServiceOrderNumber, ID_Activity, ASM, and TECH. To get the previous row for activity 2414073 you would do this:
select top(1) ASM, TECH
from OFSDA.ArchiveActivityDetails as AD
where ID_ServiceOrderNumber = 2370634229 -- same ServiceOrderNumber
and ID_Activity < 2414073 -- previous activities
order by ID_Activity desc -- highest activity less than 2414073
Instead of cross apply, you probably want to use outer apply. This is the same but you will get a row in your main query for the first activity, it will just have nulls for values in your apply. If you want the first row omitted from your results because it doesn't have a previous row, go ahead and use cross apply.
You can just put the above query into the parenthesis in outer apply() and add an alias (Previous). You link to the values for the current row in your main query, use top(1) to get the first row only, and order by ID_Activity descending to get the row with the highest ID_Activity.
select ASM, TECH,
PreviousASM, PreviousTECH
from OFSDA.ArchiveActivityDetails as AD
outer apply (
select top(1) ADInner.ASM as PreviousASM, ADInner.TECH as PreviousTECH
from OFSDA.ArchiveActivityDetails as ADInner
where ADInner.ID_ServiceOrderNumber = AD.ID_ServiceOrderNumber
and ADInner.ID_Activity < AD.ID_Activity
order by ADInnerID_Activity desc
) Previous
where ID_ServiceOrderNumber = 2370634229