Are you using a presentation variable to display the selected date in column header of your table?
Assuming you are using a presentation variable you can add a format mask to it:
This will give you your "Dec/2014" on the screen.
Yes, that's working.
I have the same scenario like this ..
In the report, I am calculating the Current Month YTD and Previous month YTD and I am using the column heading as presentation variable for current month. And also I need to get the Previous month for Previous month YTD.
When I select the prompt as Dec-14, the column heading displays current month as Dec-14 and for the Previous month I need to get it as Nov-14.
How can we achieve this. Is this possible using presentation variable?
Where does the previous month come from? Is it in a variable?
I'm almost sure it's not a variable, so can't add it in the column heading for now: problem solved ...
If you now change the question to makes it "how do I get the previous month in a presentation variable so I can use it in the column heading field", this is a new question not related with the first one. I would suggest to start a new thread for it or this thread will become "how do I make my report piece by piece" and so it will be useless for anybody else but you. As this is a community forum threads are supposed to be helpful for a maximum of people, it's why they are supposed to be single-topic.
So close this one, flag the required posts to help others looking on how to format a date presentation variable and start a new one focusing only on your new question.