How to check a parameter for legitimate blank value?

Question

Hi,
I have a parameter with a drop down for a standard field from table BSEG. There are 3 possible values in the drop down, i.e. blank, 1, or, C.
If the user enters '1' or 'C' there is no problem I can use this value in my code, i.e. I can select from BSEG where this value is a '1' or a 'C'.
How can I differentiate between an initial value in the parameter and a ' ', i.e. if the user doesn't select a value in this parameter the I need to get all BSEG records, but if the user selects ' ' for this parameter I need to get all values from BSEG where this field = ' '.

Answer 1

Hi,
Use the below code.
parameters: p_list as listbox visible length 20.
initialization.
type-pools vrm.
data: v_id type vrm_id,
      i_list type vrm_values,
      wa_list like line of i_list.
v_id = 'P_LIST'.
wa_list-key = '1'.
wa_list-text = '1'.
append wa_list to i_list.
wa_list-key = 'C'.
wa_list-text = 'C'.
append wa_list to i_list.
wa_list-key = ''.
wa_list-text = ''.
append wa_list to i_list.
*p_list = '3'.  "this is to set the default value of the list box.
CALL FUNCTION 'VRM_SET_VALUES'
  EXPORTING
    id                    = v_id
    values                = i_list
EXCEPTIONS
   ID_ILLEGAL_NAME       = 1
   OTHERS                = 2
IF sy-subrc <> 0.
MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
        WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
start-of-selection.
if not p_list is initial.
select * from BSEG into table itab where field = p_list.
else.
select * from BSEG into table itab where field is initial.
endif.