Ihave hierarchy like this
Year -Quarter -Month
2011
Q1 2011
Jan 2011
Feb 2011
Mar 2011
Now if i select July 2011 it should display in crosstab last 3 quarters including the present quarter
i.e July 2011,Mar 2011, Dec 2010,Sep 2010
Are you wanting the same month of the last three quarters or all months of the last three quarters? Because the two would make the formula much different.
For example:
you can do lead(?parameter month?, 3) to get the three months following, or lag(?parameter month?, 3) to get three months prior.