Dynamic cumulative Value in Bex report

Question

Hi
I need to implement the following report but meet problem,
User-input variables:
Year: (single value variable ready for input)
for instance 2005
Period: (interval variable ready for input)
for instance from 4 to 6
The report should display as follows:
Period 4         | Period 5 | Period 6

Answer 1

Sorry, continue as follows:
For each Period there are two kfigs should display
Amount and Cumulative amount, the cumulative amount means the amount accumulated from period 1 to current period, the report should display like
Period 04 | Period 05 | Period 06
Amout ***.Amount | Amount ***.Amount | Amount ***.Amount
Normally we can enable "cumulative" flag in key figure setting, however, the cumulative function only works for the displayed columns, e.g. the ***.amount of period 05 is the sum of amount period 04 and amount period 05, but we need the sum of amount from period 01 to period 05.
I am considering the following solutions but need your suggestion:
1. Use customer-exit variable to add the selection "from period 1 to period X",here in this case "from period 1 to period 3", and calculate the ***. amout in virtual key figure, but I have no idea how to hide the column period 1 to period X in exit.
2. Define 24 predefined fixed key figures(12 columns for amount and 12 for cumulative amount), but I have no idea how to let user filter on key figure name (1KYFNM?) when executing the query.
3. Use VBA and Web Table interface to hide the columns at runtime, but I have no idea whether if it still works when user drill down the key figures to the rows.
Any suggestion is highly appreciated!!!
it's urgent!!!
Thanks in advance,
Patrick