Hi
you can use tcode STVARV to Create a dynamic variant for it in the Selection Options tab.
or something like given below code .
REPORT zupdate_tvarv.
TABLES : tvarvc.
DATA : it_tvarvc TYPE STANDARD TABLE OF tvarvc WITH HEADER LINE ,
wa_tvarvc TYPE tvarv .
DATA: end_date TYPE /sapapo/cdps_date_to,
start_date TYPE /sapapo/cdps_date_to,
start_date1 TYPE /sapapo/cdps_date_to,
t_date TYPE /sapapo/cdps_eval_date_from ,
end_month TYPE sy-datum,
month TYPE i .
SELECTION-SCREEN BEGIN OF BLOCK b1.
PARAMETERS : p_datum TYPE sy-datum DEFAULT sy-datum.
SELECTION-SCREEN END OF BLOCK b1.
PERFORM curr_month_start.
MODIFY tvarvc FROM TABLE it_tvarvc.
COMMIT WORK .
*&---------------------------------------------------------------------*
*& Form CURR_MONTH_START
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
FORM curr_month_start.
CONCATENATE p_datum+4(2) p_datum(4) INTO t_date .
PERFORM get_period USING t_date CHANGING end_date start_date .
it_tvarvc-name = 'CURR_MONTH_START' .
it_tvarvc-type = 'P'.
it_tvarvc-low = start_date .
APPEND it_tvarvc ." to it_TVARVc.
CLEAR : t_date ,end_date, start_date ,it_tvarvc.
ENDFORM.