Prior Month problem

[lauriesamh]

I'm quite new to Cognos. My goal is to report "Current Month" (based on a YYYY-MM) parameter and then also report the prior month(and in the case where current month is January,then December of the prior year).

My parameter is based on a Varchar date field YYYY-MM.

I created a current month query that works fine.
I also created a prior month query but had to cast the varchar date to get the prior month to the current parameter.
--------------------------------
if
((cast((substring(?From Date?,6,2)), Integer)-1)<10)
then
(substring(?From Date?,1,5)+'0'+(Cast((cast((substring(?From Date?,6,2)), Integer)-1),CHARACTER)))
else
(substring(?From Date?,1,5)+(Cast((cast((substring(?From Date?,6,2)), Integer)-1),CHARACTER)))
---------------------------------
When I create a union query to combine the data from both to do percentage changes, I only get the current month data and the prior month doesn't pass through. I beleive it is due to the prior month needing the parameter date which it doesn't recognize.

Does anyone have any ideas?

My goal is to have a list with a List with section headers and drop a table within the list section

List section - X Category
Current Month Prior Month % Change
# Clients ### ### ##%
# Employees ### ### ##%
# Ratio Clients/employees ### ### ##%
Average Age of Clients ### ### ##%
% Demographic measure 1 ### ### ##%
% demographic measure 2 ### ### ##%