Question

Can anyone assist in a sql statement I am trying to write? I’m using SSRS r1 (either sql or ssrs solution is fine)

How do I:

• show count measure split by month and year
• for each of those months, I want to count the previous cumulative 12 months

e.g.

2012 jan: counts feb 2011 - jan 2012
2012 feb: counts mar 2011 - feb 2012
2012 mar: counts apr 2011 - mar 2012

I have started this code but it’s incorrect, however it gives you an idea of what I am trying to achieve (this issue is I have to calc month and year from a date)

select 
    count(a.measure) count
    ,month(a.StartDate)
    ,year(a.StartDate)
from
    a
where 
    a.StartDate >=  DATEADD(mm,DATEDIFF(mm,0,@datepromt)-12,0) as startdateYrAgo --1st month 1 year ago 01/01/2012 
    and a.StartDate <= DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,@datepromt)+1,0)) as startdateEOM --last day of month 31/01/2013
group by 
    month(a.StartDate)
    ,year(a.StartDate)

Answer 1

Here you have an idea for the query, it have to look something like below;

SELECT 
 periods.year
,periods.month
,measures.cnt
FROM (
    SELECT DISTINCT
      year = YEAR(StartDate)
    , month = MONTH(StartDate)
    , month_running = DATEDIFF(mm, 0, StartDate) 
    FROM a
    GROUP BY YEAR(StartDate), MONTH(StartDate), DATEDIFF(mm, 0, StartDate) 
) periods
JOIN (
    SELECT month_running = DATEDIFF(mm, 0, StartDate), cnt = COUNT(measure) 
    FROM a
    GROUP BY DATEDIFF(mm, 0, StartDate) 
) measures
ON measures.month_running BETWEEN periods.month_running - 12 AND periods.month_running - 1