How To Create Fields Dynamically For a Dynamic Internal Table?

*&-------------------------------------------------------------*
*& Example of creating an ABAP itab dynamically *
*& Then populate dynamic table and display using ALV *
*&-------------------------------------------------------------*
*&-------------------------------------------------------------*
REPORT CREATE_DYNAMIC_ITAB.

type-pools : abap, slis.
field-symbols: <fs_table> type standard table,
<fs_wa>,
<fs_field>.
data: dyn_table type ref to data,
dyn_line type ref to data,
wa_fieldcat type lvc_s_fcat,
it_fieldcat type lvc_t_fcat.

*ALV data declarations
data: fieldcatalog type slis_t_fieldcat_alv with header line,
gd_tab_group type slis_t_sp_group_alv,
gd_layout TYPE slis_layout_alv,
gd_repid like sy-repid.

selection-screen begin of block block1 with frame.
parameters: p_table(30) type c default 'SFLIGHT'.
selection-screen end of block block1.

***********************************************************************
*start-of-selection.
start-of-selection.
perform get_table_structure.
perform create_itab_dynamically.
perform get_data.
perform display_data.

*&---------------------------------------------------------------------*
*& Form get_table_structure
*&---------------------------------------------------------------------*
* Get structure of an SAP table
*----------------------------------------------------------------------*
form get_table_structure.
data : it_tabdescr type abap_compdescr_tab,
wa_tabdescr type abap_compdescr.
data : ref_table_descr type ref to cl_abap_structdescr.

* Return structure of the table.
ref_table_descr ?= cl_abap_typedescr=>describe_by_name( p_table ).
it_tabdescr[] = ref_table_descr->components[].
loop at it_tabdescr into wa_tabdescr.
clear wa_fieldcat.
wa_fieldcat-fieldname = wa_tabdescr-name .
wa_fieldcat-datatype = wa_tabdescr-type_kind.
wa_fieldcat-inttype = wa_tabdescr-type_kind.
wa_fieldcat-intlen = wa_tabdescr-length.
wa_fieldcat-decimals = wa_tabdescr-decimals.
append wa_fieldcat to it_fieldcat.
endloop.
endform. "get_table_structure

*&---------------------------------------------------------------------*
*& Form create_itab_dynamically
*&---------------------------------------------------------------------*
* Create internal table dynamically
*----------------------------------------------------------------------*
form create_itab_dynamically.
* Create dynamic internal table and assign to Field-Symbol
call method cl_alv_table_create=>create_dynamic_table
EXPORTING
it_fieldcatalog = it_fieldcat
IMPORTING
ep_table = dyn_table.
assign dyn_table->* to <fs_table>.
* Create dynamic work area and assign to Field Symbol
create data dyn_line like line of <fs_table>.
assign dyn_line->* to <fs_wa>.
endform. "create_itab_dynamically

*&---------------------------------------------------------------------*
*& Form get_data
*&---------------------------------------------------------------------*
* Populate dynamic itab
*----------------------------------------------------------------------*
form get_data.
* Select Data from table using field symbol which points to dynamic itab
select * into CORRESPONDING FIELDS OF TABLE <fs_table>
from (p_table).
endform. "get_data

*&---------------------------------------------------------------------*
*& Form display_data
*&---------------------------------------------------------------------*
* display data using ALV
*----------------------------------------------------------------------*
FORM display_data.
perform build_fieldcatalog.
perform build_layout.
perform display_alv_report.
ENDFORM. " display_data

*&---------------------------------------------------------------------*
*& Form BUILD_FIELDCATALOG
*&---------------------------------------------------------------------*
* Build Fieldcatalog for ALV Report, using SAP table structure
*----------------------------------------------------------------------*
form build_fieldcatalog.
* ALV Function module to build field catalog from SAP table structure
DATA: it_fcat TYPE slis_t_fieldcat_alv.

CALL FUNCTION 'REUSE_ALV_FIELDCATALOG_MERGE'
EXPORTING
i_structure_name = p_table
CHANGING
ct_fieldcat = it_fcat
EXCEPTIONS
inconsistent_interface = 1
program_error = 2
OTHERS = 3.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.

fieldcatalog[] = it_fcat[].
endform. " BUILD_FIELDCATALOG

*&---------------------------------------------------------------------*
*& Form BUILD_LAYOUT
*&---------------------------------------------------------------------*
* Build layout for ALV grid report
*----------------------------------------------------------------------*
form build_layout.
gd_layout-colwidth_optimize = 'X'.
endform. " BUILD_LAYOUT

*&---------------------------------------------------------------------*
*& Form DISPLAY_ALV_REPORT
*&---------------------------------------------------------------------*
* Display report using ALV grid
*----------------------------------------------------------------------*
form display_alv_report.
gd_repid = sy-repid.
call function 'REUSE_ALV_GRID_DISPLAY'
EXPORTING
i_callback_program = gd_repid
is_layout = gd_layout
it_fieldcat = fieldcatalog[]
i_save = 'X'
TABLES
t_outtab = <fs_table>
EXCEPTIONS
program_error = 1
others = 2.
endform. " DISPLAY_ALV_REPORT