Change date column dynamically

Hi everyone,

I need to allow a user to choose granularity of a report: week, month, quarter or year. I created a variable with values "week", "month", "quarter" and "year". Depending on what the user chose, I need to show the data grouped by corresponding interval. As I understand, I need somehow dynamically to change the infoobject in the column (0calweek ... 0calyear). Could it be done in BEx?