SSRS Matrix percentages - reporting-services

Question

Here's the report:
This is how I got the percentages for column the '%Change of most recent year".
=((Last(Fields!Quantity.Value,"Child") - First(Fields!Quantity.Value)) / First(Fields!Quantity.Value))`
= ((54675 - 55968)/55968 ) = -2.31%'
= ((54675 - 57849)/57849) = -5.49%'
It will always take the first year '2012' in this case and get the percentages against each other year. If I enter the years 2005,2004,2003,2002,2001 it will always take the first year and do a percentages against each additional year. 2005 to 2004, 2005 to 2003, 2005 to 2002 and so on. I can have as many as 2 column (year) to many columns.
I need to do it for the Total and Subtotal but it won't work because it's in a different scope.
data is = row Child group
Sub Total: = row Parent group
Total: = row Total group
Year = Column Period group
Query use to get result.
SELECT MEMBERSHIP_CODE
, PERIOD, COUNT(DISTINCT ID) AS Distinct_ID
, SUM(QUANTITY) AS Quantity
, '01-Personal' AS Child
, '01-Overall' AS Parent
, 'Total' as Total
FROM vf_Sshot AS vfs
INNER JOIN vProd AS vP ON vfs.PRODUCT_CODE = vP.PRODUCT_CODE
INNER JOIN vMem_Type vMT on vMT.Member_Type = vfs.Member_Type
WHERE (PERIOD IN ( (SELECT Val from dbo.fn_String_To_Table(#Periods,',',1))))
AND (vMT.MEMBER_TYPE NOT IN ('a','b','c'))
AND (vfs.STATUS IN ( 'A', 'D', 'C'))
AND (MEMBERSHIP_CODE NOT IN ('ABC', 'DEF' ))
and vP.PROD_TYPE in ('DUE','MC','SC')
and vMT.Member_Record = '1'
GROUP BY MEMBERSHIP_CODE, PERIOD
Any ideas?
How would I produce this output?
TOTAL: 57,573 58,941 57,573 61,188 57,573 61,175 57,175

Answer 1

This is the easiest way of solving your problem. In your query, identify the sum for the latest period on a separate column (you can transform your query into a CTE, so that you don't have to change your base query a lot):
WITH query AS (
SELECT MEMBERSHIP_CODE
, PERIOD, COUNT(DISTINCT ID) AS Distinct_ID
, SUM(QUANTITY) AS Quantity
, '01-Personal' AS Child
, '01-Overall' AS Parent
, 'Total' as Total
...
UNION
SELECT
...
)
SELECT
A.MEMBERSHIP_CODE,
A.PERIOD,
A.Distinct_ID,
A.Child,
A.Parent,
A.Total,
A.Quantity,
B.Quantity AS LastPeriodQuantity
FROM
query A INNER JOIN
(SELECT *, ROW_NUMBER() OVER(PARTITION BY MEMBERSHIP_CODE, Distinct_ID, Child, Parent ORDER BY PERIOD DESC) as periodOrder FROM query) B ON
A.MEMBERSHIP_CODE = B.MEMBERSHIP_CODE AND
A.DISTINCT_ID = B.DISTINCT_ID AND
A.Parent = B.Parent AND
A.Child = B.Child AND
A.Total = B.Total AND
B.PeriodOrder = 1
And then on all your totals/subtotals/columns you will be accessing a column that is being grouped/filtered by the same rules than your denominator. Your expression can remain, for all cells, something like this:
=(Fields!LastPeriodQuantity.Value - Fields!Quantity.Value) / Fields!Quantity.Value