Sort selected columns within ALV grid

Here is the simple program to sort selected columns within ALV grid.

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REPORT  ZSORT_ALV.

type-pools: SLIS.

data:
  begin of wa_SFLIGHT,
    carrid type sflight-carrid,
    connid type sflight-connid,
    FLDATE type sflight-FLDATE,
    PRICE type sflight-PRICE,
    CURRENCY type sflight-CURRENCY,
  end of wa_SFLIGHT,

  it_sflight like STANDARD TABLE OF wa_sflight,

  IT_FIELDCAT TYPE  SLIS_T_FIELDCAT_ALV WITH HEADER LINE,
  it_sort     type  SLIS_T_SORTINFO_ALV WITH HEADER LINE.


perform fill_fieldcat.

select * from SFLIGHT into corresponding fields of TABLE it_SFLIGHT.



it_sort-spos = 01.
it_sort-fieldname = 'CARRID'.
it_sort-UP            =  'X'.
it_sort-SUBTOT        = 'X'.
APPEND it_sort.

it_sort-spos = 02.
it_sort-fieldname = 'CONNID'.
it_sort-UP            =  'X'.
it_sort-SUBTOT        = 'X'.
APPEND it_sort.

CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
 EXPORTING
    IT_FIELDCAT                       = IT_FIELDCAT[]
    IT_SORT                           = IT_SORT[]
  TABLES
    t_outtab                          = it_SFLIGHT
  EXCEPTIONS
   PROGRAM_ERROR                     = 1
   OTHERS                            = 2
          .
IF sy-subrc <> 0.
ENDIF.
FORM FILL_FIELDCAT .

  IT_FIELDCAT-col_pos   = 1.
  IT_FIELDCAT-fieldname = 'CARRID'.
  IT_FIELDCAT-tabname   = 'IT_SFLIGHT'.
  IT_FIELDCAT-seltext_m = ' Carrid '.
  APPEND IT_FIELDCAT.

  IT_FIELDCAT-col_pos   = 2.
  IT_FIELDCAT-fieldname = 'CONNID'.
  IT_FIELDCAT-tabname   = 'IT_SFLIGHT'.
  IT_FIELDCAT-seltext_m = ' Connid '.
  APPEND IT_FIELDCAT.

  IT_FIELDCAT-col_pos   = 3.
  IT_FIELDCAT-fieldname = 'FLDATE'.
  IT_FIELDCAT-tabname   = 'IT_SFLIGHT'.
  IT_FIELDCAT-seltext_m = ' Date '.
  APPEND IT_FIELDCAT.

  IT_FIELDCAT-col_pos   = 4.
  IT_FIELDCAT-fieldname = 'PRICE'.
  IT_FIELDCAT-tabname   = 'IT_SFLIGHT'.
  IT_FIELDCAT-seltext_m = ' Price '.
  APPEND IT_FIELDCAT.

  IT_FIELDCAT-col_pos   = 5.
  IT_FIELDCAT-fieldname = 'CURRENCY'.
  IT_FIELDCAT-tabname   = 'IT_SFLIGHT'.
  IT_FIELDCAT-seltext_m = ' Currency '.
  APPEND IT_FIELDCAT.
ENDFORM.
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And the output is :