How to calculated Working Hours over 17 week period - sql

Question

I am trying to work out How many field engineers work over 48 hours over a 17 week period. (by law you cannot work over 48 hours over a 17 week period)
I managed to run the query for 1 Engineer but when I run it without an Engineer filter my query is very slow.
I need to get the count of Engineers working over 48 hours and count under 48 hours then get an Average time worked per week.
Note: I am doing a Union on SPICEMEISTER & SMARTMEISTER because they are our old and new databases.
• How many field engineers go over the 48 hours
• How many field engineers are under the 48 hours
• What is the average time worked per week for engineers
SELECT DS_Date
,TechPersNo
FROM
(
SELECT DISTINCT
SMDS.EPL_DAT as DS_Date
,EN.pers_no as TechPersNo
FROM
[SpiceMeister].[FS_OTBE].[EngPayrollNumbers] EN
INNER JOIN
[SmartMeister].[Main].[PlusDailyKopf] SMDS
ON RIGHT(CAST(EN.[TechnicianID] AS CHAR(10)),5) = SMDS.PRPO_TECHNIKERNR
WHERE
SMDS.EPL_DAT >= '2017-01-01'
and
SMDS.EPL_DAT < '2018-03-01'
UNION ALL
SELECT DISTINCT
SPDS.DailySummaryDate as DS_Date
,EN.pers_no as TechPersNo
FROM
[SpiceMeister].[FS_OTBE].[EngPayrollNumbers] EN
INNER JOIN
[SpiceMeister].[FS_DS_BO].[DailySummaryHeader] SPDS
ON EN.TechnicianID = SPDS.TechnicianID
WHERE
SPDS.DailySummaryDate >= '2018-03-01'
) as Techa
where TechPersNo = 850009
) Tech
cross APPLY
Fast results

Answer 1

The slowness is definitely due to the use of cross apply with a correlated subquery. This will force the computation on a per-row basis and prevents SQL Server from optimizing anything.
This seems more like it should be a 'group by' query, but I can see why you had trouble making it up on account of the complex cumulative calculation in which you need output by person and by date, but the average involves not the date in question but a date range ending on the date in question.
What I would do first is make a common query to capture your base data between the two datasets. That's what I do in the 'dailySummaries' common table expression below. Then I would join dailySummaries onto itself matching by the employee and selecting the date range required. From that, I would group by employee and date, aggregating by the date range.
with
dailySummaries as (
select techPersNo = en.pers_no,
ds_date = smds.epl_dat,
dtDif = datediff(minute, smds.abfahrt_zeit, smds.rueck_zeit)
from smartMeister.main.plusDailyKopf
join smartMeister.main.plusDailyKopf smds
on right(cast(en.technicianid as char(10)),5) = smds.prpo_technikernr
where smds.epl_dat < '2018-03-01'
union all
select techPersNo = en.pers_no,
dailySummaryDate,
datediff(minute,
iif(spds.leaveHome < spds.workStart, spds.leaveHome, spds.workStart),
iif(spds.arrivehome > spds.workEnd, spds.arrivehome, spds.workEnd)
)
from spiceMeister.fs_ds_bo.dailySummaryHeader spds
join spiceMeister.fs_ds_bo.dailySummaryHeader spds
on en.TechnicianID = spds.TechnicianID
where spds.DailySummaryDate >= '2018-03-01'
)
select ds.ds_date,
ds.techPersNo,
AvgHr = convert(real, sum(dsPrev.dtDif)) / (60*17)
from dailySummaries ds
left join dailySummaries dsPrev
on ds.techPersNo = dsPrev.techPersNo
and dsPrev.ds_date between dateadd(day,-118, ds.ds_date) and ds.ds_date
where ds.ds_date >= '2017-01-01'
group by ds_date,
techPersNo
order by ds_date
I may have gotten a thing or two wrong in translation but you get the idea.
In the future, post a more minimal example. The union of the two datasets from the separate databases is not central to the problem you were trying to ask about. A lot of the date filterings aren't core to the question. The special casting in your join match logic is not important. These things cloud the real issue.