Compare 2 dynamically created matrix columns to get a difference - reporting-services

Question

I have a matrix set up with a Row Group called "company", a Column Group called "Year" and a value field that is a sum of charges through the year called revenue. The column Group will end up having 2 columns in it that are provided through user input. The end results is a matrix that will look something like this:
Year 1 | Year 2
Company: $500 $250
Company2: $750 $250
What I would like to do is add a column to the matrix that calculates the change from year 1 to year 2. Is there a way to do this within the matrix such as adding a new column with an expression that compares the 2 entries in the row or will I need to manipulate the SQL code to create a column that does this within the code? To that end here is a view of the code for the dataset if that is the way I need to go:
SELECT
company.cmp_id
,company.Company
,ChargeDetails.[Bill To ID]
,ChargeDetails.[Delivery Year]
,ChargeDetails.Revenue
FROM
ChargeDetails
LEFT OUTER JOIN company
ON ChargeDetails.[Bill To ID] = company.cmp_id
WHERE
ChargeDetails.[Delivery Year] = #DeliveryYear
OR
ChargeDetails.[Delivery Year] = #ComparisonYear2
ORDER BY ChargeDetails.[Delivery Year] DESC,ChargeDetails.Revenue DESC;`

Answer 1

Try to add a column outside the Year group in header type Change or what you want to put, in the below cell use this expression:
=Sum(iif(Max(Fields!DeliveryYear.Value)=Fields!DeliveryYear.Value,Fields!Revenue.Value,0))-
Sum(iif(Min(Fields!DeliveryYear.Value)=Fields!DeliveryYear.Value,Fields!Revenue.Value,0))
Note I am substracting the min year (1) revenue sum to the max
year (2) revenue sum.
In your example it will produce:
+-----------+--------+--------+--------+
| Company | Year 1 | Year 2 | Change |
+-----------+--------+--------+--------+
| Company A | 500 | 250 | -250 |
+-----------+--------+--------+--------+
You can define change in many ways maybe in percentage or any other measure, this is only an example, learn what the above expression is doing in order to calculate the measure you need.
EDIT 1:
Add the matrix with this data arrangement.
The matrix looks like this one in preview:
Be sure you added the Change column outside the DeliveryYear group as shown in above image. Also check the fields names correspond to yours in the expression.
EDIT 2:
If Revenue has null values you can try this:
Try replace the null values at query level using T-SQL ISNULL() Function, change your query in this part as follows
,ISNULL(ChargeDetails.Revenue,0)
However if DeliveryYear has null values you may want to ignore that records, so try to exclude it in the where clause.
Let me know if you need further help.

Answer 2

I ended up using the following as the expression in the change column.
=sum(iif(Fields!Delivery_Year.Value=Parameters!DeliveryYear.Value,1,0)*Fields!Revenue.Value) - sum(iif(Fields!Delivery_Year.Value=Parameters!ComparisonYear2.Value,1,0)* Fields!Revenue.Value)