Question

I have a view that I want to use to generate a payroll report.
I want it such that it selects/gets the last 3 months of monthly processed data.
E.g. If today is 15th May 2012 and payroll for May has not been done, I want to get the results for April, March and February only.

My query:

SELECT  dbo.[@EIM_PROCESS_DATA].U_Tax_year, dbo.[@EIM_PROCESS_DATA].U_Employee_ID, SUM(dbo.[@EIM_PROCESS_DATA].U_Amount) AS PAYE, 
              dbo.OADM.CompnyName, dbo.OADM.CompnyAddr, dbo.OADM.TaxIdNum, dbo.OHEM.lastName + ', ' + ISNULL(dbo.OHEM.middleName, '') 
              + ' ' + ISNULL(dbo.OHEM.firstName, '') AS EmployeeName, dbo.OHEM.govID, dbo.[@EIM_PROCESS_DATA].U_Process_month
FROM     dbo.[@EIM_PROCESS_DATA] INNER JOIN
               dbo.OHEM ON dbo.[@EIM_PROCESS_DATA].U_Employee_ID = dbo.OHEM.empID CROSS JOIN
               dbo.OADM
WHERE   (dbo.[@EIM_PROCESS_DATA].U_PD_code = 'SYS033')
GROUP BY dbo.[@EIM_PROCESS_DATA].U_Tax_year, dbo.[@EIM_PROCESS_DATA].U_Employee_ID, dbo.OADM.CompnyName, dbo.OADM.CompnyAddr, dbo.OADM.TaxIdNum, 
                      dbo.OHEM.lastName, dbo.OHEM.firstName, dbo.OHEM.middleName, dbo.OHEM.govID, dbo.[@EIM_PROCESS_DATA].U_Process_month

The field U_Process_Month stores the name of the months of the year (varchar). Any help?

Answer 1

Here is one option if you want to turn a month name into a datetime:

declare @Month varchar(10) = 'DEC'
declare @Year varchar(4) = '2012'

SELECT CAST(@Month ' ' + @Year AS DATETIME) AS KeyDate

Replace the @Month and @Year variables with your field names, and you have the first step 😉

For selecting only the last three months, try the HAVING clause, together with a variable @MaxKeydate that indicates the last processed month:

SELECT (...) FROM bla
HAVING KeyDate > DATEADD(month, -3, @MaxKeyDate)

You need to see yourself, if you can determine the value for @MaxKeyDate with a simple

SELECT MAX(CAST(@Month ' ' + @Year AS DATETIME)) FROM bla

or if it is more complicated.