Firsr step in alv-simple program

**mandatory Fields required for alv

TYPE-POOLS:slis.

DATA:w_repid LIKE sy-repid.

DATA:fs_layout TYPE slis_layout_alv.

DATA: t_fieldcat TYPE slis_t_fieldcat_alv,
fs_fieldcat TYPE slis_fieldcat_alv.
*********************************************
DATA:BEGIN OF fs_string,
carrid LIKE spfli-carrid,
connid LIKE spfli-connid,
countryfr LIKE spfli-countryfr,
countryto LIKE spfli-countryto,
END OF fs_string.
DATA:t_spfli LIKE TABLE OF fs_string.


PERFORM get_data.
PERFORM prepare_fieldcatalog.
PERFORM display_output.


*&---------------------------------------------------------------------*
*& Form prepare_fieldcatalog
*&---------------------------------------------------------------------*
* Fills data to the fieldcatalaog
*----------------------------------------------------------------------*
FORM prepare_fieldcatalog .


fs_fieldcat-col_pos = 1.
fs_fieldcat-fieldname = 'CARRID'.
fs_fieldcat-seltext_m = 'Airlinecarrier'.
fs_fieldcat-key = 'X'.
fs_fieldcat-hotspot = 'X'.
APPEND fs_fieldcat TO t_fieldcat.
CLEAR fs_fieldcat.


fs_fieldcat-col_pos = 2.
fs_fieldcat-fieldname = 'CONNID'.
fs_fieldcat-seltext_m = 'Connectionid'.
APPEND fs_fieldcat TO t_fieldcat.
CLEAR fs_fieldcat.


fs_fieldcat-col_pos = 3.
fs_fieldcat-fieldname = 'COUNTRYFR'.
fs_fieldcat-seltext_m = 'Countryfrom'.
APPEND fs_fieldcat TO t_fieldcat.
CLEAR fs_fieldcat.


fs_fieldcat-col_pos = 4.
fs_fieldcat-fieldname = 'COUNTRYTO'.
fs_fieldcat-seltext_m = 'Countryto'.
APPEND fs_fieldcat TO t_fieldcat.
CLEAR fs_fieldcat.


ENDFORM. " prepare_fieldcatalog


*&---------------------------------------------------------------------*
*& Form get_data
*&---------------------------------------------------------------------*
* Fetch data from database table to internal table
*----------------------------------------------------------------------*
FORM get_data .


SELECT carrid
connid
countryfr
countryto
FROM spfli
INTO CORRESPONDING FIELDS OF TABLE t_spfli.
w_repid = sy-repid.

ENDFORM. " get_data
*&---------------------------------------------------------------------*
*& Form DISPLAY_OUTPUT
*----------------------------------------------------------------------*
* Function module to display ALV
*----------------------------------------------------------------------*
FORM display_output .


CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
EXPORTING
i_callback_program = w_repid
it_fieldcat = t_fieldcat[]
TABLES
t_outtab = t_spfli
* EXCEPTIONS
* PROGRAM_ERROR = 1
.
Endform.