Conditional SUM in SQL Server 2014 - sql

Question

I am using SQL Server 2014. When I was testing my code I noticed a problem.
Assume that max personal hour is 80 hours.
SELECT
lsm.EmployeeName,
pd.absenceDate,
pd.amountInDays * 8 AS [HoursReported],
pd.status,
(SUM(CASE WHEN pd.[status]='App' THEN (pd.amountInDays * 8)
ELSE 0 END) OVER (partition by lsm.[EmployeeName] order by pd.absenceDate)) AS [TotalUsedHours]
( #maxPSHours ) - (sum(
CASE WHEN pd.[status]='App' THEN (pd.amountInDays * 8)
ELSE 0 END)
over (
partition by lsm.[EmployeeName] order by pd.absenceDate)) AS [TotalRemainingHours]
FROM
[LocationStaffMembers] lsm
INNER JOIN
[PersonalDays] pd ON lsm.staffMemberId = pd.staffMemberId
This query returns these results:
EmployeeName AbsenceDate HoursReported Status TotalUsdHrs TotalRemingHrs
X 11/11/2015 4 approved 4 76
X 11/15/2015 8 approved 12 68
X 11/20/2015 2 decline 14 66
X 11/20/2015 2 approved 14 66
So, query works fine for different status. First 2 rows are fine. But when an employee does more than one action in a day (decline, approved etc.), my query only shows the total used and total remaining for the day.
Here is the expected result.
EmployeeName AbsenceDate HoursReported Status TotalUsdHrs TotalRemingHrs
X 11/11/2015 4 approved 4 76
X 11/15/2015 8 approved 12 68
X 11/20/2015 2 decline 12 68
X 11/20/2015 2 approved 14 66

Answer 1

You are doing a cumulative sum that returns results based on the order of AbsenceDate (sum(...) over (partition by ... order by pd.absenceDate). But your last 2 records have the exact same date (11/20/2015) -- at least, according to what you are showing us. This creates an ambiguity.
So, it is absolutely conceivable, and legal, that SQL Server is processing the 2 approved hours row before the 2 declined hours row when calculating the cumulative sum --which would explain your current results--, despite the fact that rows themselves are returned to you in a different order (BTW, consider adding an order by clause to the query, otherwise, the order of the rows themselves are not guaranteed).
If the 2 rows do in fact share the exact same date, you'll have to find a 2nd column to remove the ambiguity and add that to the order by clause in the cumulative sum window function. Maybe you could add a timestamp field that you can order by.
Or maybe you always want the declined status to be considered ahead of the approved status when the AbsenceDate is the same. Here is an example of a query that would do exactly that (notice the changes in the order by clauses):
SELECT
lsm.EmployeeName,
pd.absenceDate,
pd.amountInDays * 8 AS [HoursReported],
pd.status,
(SUM(CASE WHEN pd.[status]='App' THEN (pd.amountInDays * 8)
ELSE 0 END) OVER (partition by lsm.[EmployeeName] order by pd.absenceDate,
case when pd.[status] = 'App' then 1 else 0 end)) AS [TotalUsedHours]
( #maxPSHours ) - (sum(
CASE WHEN pd.[status]='App' THEN (pd.amountInDays * 8)
ELSE 0 END)
over (
partition by lsm.[EmployeeName] order by pd.absenceDate,
case when pd.[status] = 'App' then 1 else 0 end)) AS [TotalRemainingHours]
FROM
[LocationStaffMembers] lsm
INNER JOIN
[PersonalDays] pd ON lsm.staffMemberId = pd.staffMemberId
ORDER BY lsm.[EmployeeName],
pd.absenceDate,
case when pd.[status] = 'App' then 1 else 0 end