* If you have two parameters, you want to display values(f4) in parameter 2 
* depending on the values entered in parameter 1.

REPORT Z_SRI_HELP_VALUE_FOR_TABLES .

tables tcurt.
DATA   DYFIELDS LIKE DYNPREAD OCCURS 1 WITH HEADER LINE.
PARAMETERS: P_WAERS LIKE TCURT-WAERS,        "Currency
            P_LTEXT LIKE TCURT-LTEXT,        "Long Text
            P_KTEXT LIKE TCURT-KTEXT.        "Short Text
*-----------------------------------------------------------------------
*--- Example of updating value of another field on the screen ----------
AT SELECTION-SCREEN ON VALUE-REQUEST FOR P_WAERS.
  CLEAR: DYFIELDS[], DYFIELDS.
*--- select currency
  CALL FUNCTION 'HELP_VALUES_GET'
       EXPORTING
            fieldname        =  'WAERS'
            tabname          =  'TCURT'
       IMPORTING
            SELECT_VALUE     =   P_WAERS.
*--- get long text for the selected currency
  SELECT SINGLE LTEXT FROM TCURT
    INTO DYFIELDS-FIELDVALUE
    WHERE SPRAS = SY-LANGU
    AND   WAERS = P_WAERS.
  IF SY-SUBRC <> 0.
    CLEAR DYFIELDS-FIELDVALUE.
  ENDIF.
*--- update another field
  DYFIELDS-FIELDNAME = 'P_LTEXT'.
  APPEND DYFIELDS.
  CALL FUNCTION 'DYNP_VALUES_UPDATE'
       EXPORTING
            DYNAME               = SY-CPROG
            DYNUMB               = SY-DYNNR
       tables
            dynpfields           = DYFIELDS .
*-----------------------------------------------------------------------
*--- Example of reading value of another field -------------------------
AT SELECTION-SCREEN ON VALUE-REQUEST FOR P_KTEXT.
*--- read another field
  CLEAR: DYFIELDS[], DYFIELDS.
  DYFIELDS-FIELDNAME = 'P_WAERS'.
  APPEND DYFIELDS.
  CALL FUNCTION 'DYNP_VALUES_READ'
       EXPORTING
            DYNAME                   = SY-CPROG
            DYNUMB                   = SY-DYNNR
       TABLES
            DYNPFIELDS               = DYFIELDS .
  READ TABLE DYFIELDS INDEX 1.
*--- get short text and update current field
  SELECT SINGLE KTEXT FROM TCURT
    INTO P_KTEXT
    WHERE SPRAS EQ SY-LANGU
    AND   WAERS EQ DYFIELDS-FIELDVALUE.
*-----------------------------------------------------------------------

How to add F4 functionality to a paramter variable?  Say P_name ie Parameters: P_name like dbtab-fieldname
in At selection-screen on value-request for p_name.  How should I add the values john, abraham, linga etc so that these values appear when f4 is pressed on the field in the selection screen?

PARAMETERS: p_name(10).
DATA: BEGIN OF value_tab OCCURS 0,
               name(10),
             END OF value_tab.
DATA :field_tab LIKE dfies  OCCURS 0 WITH HEADER LINE.
DATA : return_tab LIKE ddshretval OCCURS 0 WITH HEADER LINE. DATA : x TYPE string.

  AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_name.

  REFRESH value_tab[].
  REFRESH field_tab[].
  REFRESH return_tab[].
    field_tab-fieldname = 'ERNAM'.
  field_tab-tabname = 'VBAK'.
  APPEND field_tab.
    value_tab-name = 'John'.
  APPEND value_tab.
  value_tab-name = 'Abraham'.
  APPEND value_tab.
  value_tab-name = 'Lingam'.
  APPEND value_tab.

    CALL FUNCTION 'F4IF_INT_TABLE_VALUE_REQUEST'
    EXPORTING
      retfield        = field_tab-fieldname
    TABLES
      value_tab       = value_tab
      field_tab       = field_tab
      return_tab      = return_tab
    EXCEPTIONS
      parameter_error = 1
      no_values_found = 2
      OTHERS          = 3.
  IF sy-subrc = 0.
    p_name = return_tab-fieldval.
  ENDIF.

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