How do I case sum a column based on a value - 1? - sql

Question

So I have the following 2 columns
,sum(case when Owner_Faculty_Full_Desc = 'Business and Law Faculty' then 1 else 0 end) [Business Current Year]
,sum(case when Owner_Faculty_Full_Desc = 'Business and Law Faculty' AND Apps.Reporting_Year = (Apps.Reporting_Year - 1) then 1 else 0 end) [Business Previous Year]
Lets say that Apps.ReportingYear is 2011, how to I get the second column to sum all values in 2010? I thought my statement would work but it doesn't seem to be.
Here is the entire query
WITH Equiv_day AS (
SELECT Date_Key, Sem1_Equivalent_Day
FROM [AUTDataWarehouse].[dbo].[Dim_Date]
WHERE Full_Date = CONVERT(DATE, GETDATE())
),
Date_list AS (
SELECT dt.Date_Key, dt.Calendar_Year
FROM [AUTDataWarehouse].[dbo].[Dim_Date] AS dt
INNER JOIN Equiv_day AS ed
ON (ed.Sem1_Equivalent_Day - 1) = dt.Sem1_Equivalent_Day
AND dt.Calendar_Year IN (YEAR(GETDATE()), YEAR(GETDATE())-1, YEAR(GETDATE()) - 2, YEAR(GETDATE()) - 3, YEAR(GETDATE()) - 4, YEAR(GETDATE()) - 5)
),
PYTD_Outcome_by_Application AS (
SELECT
se.Reporting_Year,
f.Student_Demographics_Key,
f.Application_Code,
Outcome_Row = Max(f.Application_Row_Num)
FROM AUTDataWarehouse.dbo.Fact_Admission as f
INNER JOIN AUTDataWarehouse.dbo.Dim_Intake as it
ON it.Intake_Key = f.Intake_Key
AND it.Prog_Intake_Type_Desc = 'Intake'
INNER JOIN AUTDataWarehouse.dbo.Dim_Semester as se
ON se.Semester_Key = f.Semester_Key
INNER JOIN AUTDataWarehouse.dbo.Dim_Campus as cp
ON cp.Campus_Key = f.Campus_Key
INNER JOIN Date_list as dates
ON dates.Calendar_Year = se.Reporting_Year
WHERE f.Last_Change_Date_Key < dates.Date_Key
GROUP BY
se.Reporting_Year,
f.Student_Demographics_Key,
f.Application_Code
),
Applications_Count AS (
SELECT
p.Owner_Faculty_Full_Desc,
p.Programme_Full_Desc,
et.Enrolment_Type_Key,
se.Reporting_Year,
sd.Last_Secondary_School_Name [LastSchoolName],
pr.Programme_Key,
Campus = CASE WHEN cp.Campus_Name IN ('South','South Dist') THEN 'South' ELSE 'City / North Shore' END,
se.Semester_Desc,
f.Student_Demographics_Key,
Applicants = COUNT(DISTINCT f.Student_Demographics_Key)
FROM AUTDataWarehouse.dbo.Fact_Admission as f
INNER JOIN AUTDataWarehouse.dbo.Dim_Student_Demographics as sd ON sd.Student_Demographics_Key = f.Student_Demographics_Key
INNER JOIN AUTDataWarehouse.dbo.Dim_Programme as P on P.Programme_Key = f.Programme_Key
INNER JOIN AUTDataWarehouse.dbo.Dim_Intake as it
ON it.Intake_Key = f.Intake_Key
AND it.Prog_Intake_Type_Desc = 'Intake'
INNER JOIN AUTDataWarehouse.dbo.Dim_Enrolment_Type as et
ON et.Enrolment_Type_Key = f.Enrolment_Type_Key
INNER JOIN AUTDataWarehouse.dbo.Dim_Programme as pr
ON pr.Programme_Key = f.Programme_Key
INNER JOIN AUTDataWarehouse.dbo.Dim_Campus as cp
ON cp.Campus_Key = f.Campus_Key
INNER JOIN AUTDataWarehouse.dbo.Dim_Semester as se
ON se.Semester_Key = f.Semester_Key
INNER JOIN Date_list as dates
ON dates.Calendar_Year = se.Reporting_Year
INNER JOIN PYTD_Outcome_by_Application AS pytd
ON pytd.Application_Code = f.Application_Code
AND pytd.Student_Demographics_Key = f.Student_Demographics_Key
AND pytd.Outcome_Row = f.Application_Row_Num
and pytd.Reporting_Year = se.Reporting_Year
AND pytd.Application_Code IS NOT NULL
GROUP BY
sd.Last_Secondary_School_Name,
p.Owner_Faculty_Full_Desc,
p.Programme_Full_Desc,
et.Enrolment_Type_Key,
se.Reporting_Year,
pr.Programme_Key,
CASE WHEN cp.Campus_Name IN ('South','South Dist') THEN 'South' ELSE 'City / North Shore' END,
se.Semester_Desc,
f.Student_Demographics_Key
)
SELECT
CAST(EP.Educational_Provider_Key as varchar(10)) as 'Education Key'
,[LastSchoolName]
,Owner_Faculty_Full_Desc
,Programme_Full_Desc
,Apps.Reporting_Year
,cast(cast(Apps.Reporting_Year as varchar(255)) + '0101' as datetime) as [YearTime]
,sum(case when Owner_Faculty_Full_Desc = 'Business and Law Faculty' then 1 else 0 end) [Business and Law Current Year]
,sum(case when Owner_Faculty_Full_Desc = 'Business and Law Faculty' AND (Apps.Reporting_Year = Apps.Reporting_Year - 1) then 1 else 0 end) [Business and Law Previous Year]
,sum(case when Owner_Faculty_Full_Desc = 'Culture and Society Faculty' then 1 else 0 end) [Culture and Society Current Year]
,sum(case when Owner_Faculty_Full_Desc = 'Culture and Society Faculty' AND Apps.Reporting_Year = 2014 then 1 else 0 end) [Culture and Society Previous Year]
,sum(case when Owner_Faculty_Full_Desc = 'Design & Creative Technologies Faculty'then 1 else 0 end) [Design & Creative TechnologiesCurrent Year]
,sum(case when Owner_Faculty_Full_Desc = 'Design & Creative Technologies Faculty' AND Apps.Reporting_Year = (Apps.Reporting_Year - 1) then 1 else 0 end) [Design & Creative Technologies Previous Year]
,sum(case when Owner_Faculty_Full_Desc = 'Health & Environmental Sciences Faculty'then 1 else 0 end) [Health & Environmental Sciences Current Year]
,sum(case when Owner_Faculty_Full_Desc = 'Health & Environmental Sciences Faculty' AND Apps.Reporting_Year = (Apps.Reporting_Year - 1) then 1 else 0 end) [Health & Environmental Sciences Previous Year]
,sum(case when Owner_Faculty_Full_Desc = 'Te Ara Poutama' then 1 else 0 end) [Te Ara Poutama Current Year]
,sum(case when Owner_Faculty_Full_Desc = 'Te Ara Poutama' AND Apps.Reporting_Year = (Apps.Reporting_Year - 1) then 1 else 0 end) [Te Ara Poutama Previous Year]
,sum(apps.Applicants) [Total Applicants]
FROM Applications_Count as Apps
inner join AUTDataWarehouse.dbo.Dim_Educational_Provider as EP on EP.Provider_Name = [LastSchoolName]
GROUP BY Apps.Reporting_Year, [LastSchoolName], EP.Educational_Provider_Key,Owner_Faculty_Full_Desc
, Programme_Full_Desc
ORDER BY Apps.Reporting_Year, [Total Applicants] DESC
So basically for each programme I want a column for total applicants for the ReportingYear then total applicants for the Reporting Year - 1
Thanks!

Answer 1

Probably easiest to calculate the years separately, then self-join to get the value for the previous year. This is the basic logic you would use, although obviously you will need to make it more complex when you adapt it to the long query above:
;with CTE as (select ReportingYear
, sum(case when [condition] then 1 else 0 end) as ValueCurrYear
from MyTables
group by ReportingYear)
Select a.*, b.ValueCurrYear as ValuePreviousYear
from CTE a
left join CTE b
on a.ReportingYear = b.ReportingYear + 1