Set Default value in Module Pool for particular field.

Hi,

hgv.png

I have created one Module Pool Program. when user enters truck number and clicks on Get data, below information is coming From Ztable (Attached SS). and I want to set default non editable value for cost Center which is not maintained in ztable and after click on save it should save in ztable. How do i Fix cost center value ?

MODULE USER_COMMAND_0100 INPUT.
  CASE SY-UCOMM.
    WHEN 'GET'.
      SELECT SINGLE * FROM ZDAILY WHERE TRUCK_NO = ZDAILY-TRUCK_NO.
*      
    WHEN 'SAVE'.
      IF ZDAILY IS NOT INITIAL.
        UPDATE ZDAILY.


*         INSERT zhgvt.
        PERFORM TCLEAR.
      ENDIF.

    WHEN 'DIS'.
      CALL TRANSACTION 'ZDAILY_HGV'.
    WHEN 'BACK' OR 'EXIT' OR 'CANCEL'.
      LEAVE TO SCREEN 0.
    WHEN 'HGV' .
      CALL TRANSACTION 'ZDAILY_HGV1'.
      CLEAR HGV.
    WHEN 'LV'.
      CALL TRANSACTION 'ZDAILY_LV'.
      CLEAR LV.
  ENDCASE.
*clear : sy-ucomm.
ENDMODULE.