show column value in 'previous row' and in a new column - sql

Question

I have a table with four columns; Plant_Id, Year, Month and MR. I would like to be able to calculate the Range (month 2 month difference) of MR.
A sample of the table (MaintenanceRatebepaen is the table name) looks like this:
Plant_ID Year Month MR
CCAR 2009 1 0,706452
CCAR 2009 2 0,625899
CCAR 2009 3 0,636678
CCAR 2009 4 0,736544
CCAR 2009 5 0,552023
CCAR 2009 6 0,418338
CCAR 2009 7 0,502732
CCAR 2009 8 0,64526
CCAR 2009 9 0,743333
CCAR 2009 10 0,555556
CCAR 2009 11 0,297561
CCAR 2009 12 0,338608
CCAR 2010 1 0,380783
Etc.
I'm not sure this is of interest, but Plant_id can have 25 different values, years from 2008 - 2012, months 1-12, MR is a calculated value.
The Query looks like this:
SELECT Plant_Id, Jaar, Maand
, (SUM(Compl) + 0.000) / SUM(Total) AS MR
FROM (
SELECT Plant_Id, Jaar, Late, EarlyJobs, OnTimeJobs, Maand
, SUM(EarlyJobs + OnTimeJobs) AS Compl
, SUM(EarlyJobs) + SUM(Late) + SUM(OnTimeJobs) AS Total
FROM MaintenanceRatebepaen AS MaintenanceRatebepaen_1
GROUP BY Plant_Id, Jaar, Maand, Late, OnTimeJobs, EarlyJobs
) AS MaintenanceRatebepaen
WHERE (Jaar >= 2009) AND (Jaar <= 2011) AND (Plant_Id = 'CCAR')
GROUP BY Jaar, Plant_Id, Maand
ORDER BY Plant_Id, Jaar, Maand
I'm new to SQL, I managed to get the above from books and google searches. But I can't get the Range calculated, any help is greatly appreciated!

Answer 1

Did you just want month by month differences?
Data
declare #data table (PlantId nvarchar(5), [Year] nvarchar(4), [Month] int, MR decimal(10,10))
INSERT #data VALUES
('CCAR','2009','1','0.706452'),('CCAR','2009','2','0.625899'),('CCAR','2009','3','0.636678'),('CCAR','2009','4','0.736544'),('CCAR','2009','5','0.552023'),('CCAR','2009','6','0.418338'),('CCAR','2009','7','0.502732'),('CCAR','2009','8','0.64526'),('CCAR','2009','9','0.743333'),('CCAR','2009','10','0.555556'),('CCAR','2009','11','0.297561'),('CCAR','2009','12','0.338608'),('CCAR','2010','1','0.380783')
Query
;with cte as (
SELECT *, ROW_NUMBER() OVER (ORDER BY Year DESC, Month DESC) AS RowNumber FROM #data
)
select d1.PlantId
, d1.Year
, d1.Month
, d1.MR
, d1.MR-d2.MR AS [ChangeMRFromPreviousMonth]
from cte d1
LEFT OUTER JOIN cte d2
on d2.RowNumber = (d1.RowNumber+1)
order by d1.RowNumber DESC
Results:
PlantId Year Month MR ChangeMRFromPreviousMonth
------- ---- ----------- --------------------------------------- ---------------------------------------
CCAR 2009 1 0.7064520000 NULL
CCAR 2009 2 0.6258990000 -0.0805530000
CCAR 2009 3 0.6366780000 0.0107790000
CCAR 2009 4 0.7365440000 0.0998660000
CCAR 2009 5 0.5520230000 -0.1845210000
CCAR 2009 6 0.4183380000 -0.1336850000
CCAR 2009 7 0.5027320000 0.0843940000
CCAR 2009 8 0.6452600000 0.1425280000
CCAR 2009 9 0.7433330000 0.0980730000
CCAR 2009 10 0.5555560000 -0.1877770000
CCAR 2009 11 0.2975610000 -0.2579950000
CCAR 2009 12 0.3386080000 0.0410470000
CCAR 2010 1 0.3807830000 0.0421750000
Is that what you needed? Your query contains alot of extra columns, so I don't know if you want that including?
* Edit *
In response to your comments, you need to put your query inside the CTE, with the additional RowNumber column. d1 and d2 are just aliases of that CTE. I think this should do it:
;with cte as (
SELECT Plant_Id, Jaar, Maand
, (SUM(Compl) + 0.000) / SUM(Total) AS MR
, ROW_NUMBER() OVER (ORDER BY Jaar DESC, Maand DESC) AS RowNumber
FROM (
SELECT Plant_Id, Jaar, Late, EarlyJobs, OnTimeJobs, Maand
, SUM(EarlyJobs + OnTimeJobs) AS Compl
, SUM(EarlyJobs) + SUM(Late) + SUM(OnTimeJobs) AS Total
FROM MaintenanceRatebepaen AS MaintenanceRatebepaen_1
GROUP BY Plant_Id, Jaar, Maand, Late, OnTimeJobs, EarlyJobs
) AS MaintenanceRatebepaen
WHERE (Jaar >= 2009) AND (Jaar <= 2011) AND (Plant_Id = 'CCAR')
GROUP BY Jaar, Plant_Id, Maand
ORDER BY Plant_Id, Jaar, Maand
)
select d1.PlantId
, d1.Jaar
, d1.Maand
, d1.MR
, d1.MR-d2.MR AS [ChangeMRFromPreviousMonth]
from cte d1
LEFT OUTER JOIN cte d2
on d2.RowNumber = (d1.RowNumber+1)
order by d1.RowNumber DESC