Can we create internal table dynamically ? how?

Question

hi to all experts,
                       can we create internal table dynamically ? how?plz explain me with an example.Anybody with good example  will be rewarded.it was asked in an interview what the answer for it

Answer 1

HI
Yes you can create
see this
/people/rich.heilman2/blog/2005/07/27/dynamic-internal-tables-and-structures--abap
JUST USE THIS CODE AND DO THE ESSENTIAL CHANGES ACCORDING TO YOU
STEP: 1 - get backend field catalog (currently displayed alv)
CLEAR: tl_fieldcatalog. REFRESH: tl_fieldcatalog.
CALL METHOD w_grid->get_backend_fieldcatalog
IMPORTING
et_fieldcatalog = tl_fieldcatalog.
STEP: 2 - create a new fieldcatalog for dynamic internal table
CLEAR: sl_fieldcatalog.
CLEAR: t_outtab_fieldname. REFRESH: t_outtab_fieldname.
CLEAR: tl_fieldcatalog_new. REFRESH: tl_fieldcatalog_new.
CLEAR: t_download_fieldname. REFRESH: t_download_fieldname.
CLEAR: t_download_fieldheading. REFRESH: t_download_fieldheading.
LOOP AT tl_fieldcatalog INTO sl_fieldcatalog.
STEP: 2.1 - populate data in T_OUTTAB_FIELDNAME
APPEND sl_fieldcatalog-fieldname TO t_outtab_fieldname.
STEP: 2.2 - populate TL_FIELDCATALOG_NEW & T_DOWNLOAD_FIELDNAME
IF sl_fieldcatalog-no_out EQ ''.
IF sl_fieldcatalog-fieldname NE 'STATUS'
OR sl_fieldcatalog-fieldname NE 'MESG_STATUS'
OR sl_fieldcatalog-fieldname NE 'ZLOCK'
OR sl_fieldcatalog-fieldname NE 'T_PLANT'
OR sl_fieldcatalog-fieldname NE 'T_CSR'.
If field is COMM_PLANT, change its length
IF sl_fieldcatalog-fieldname EQ 'COMM_PLANT'.
sl_fieldcatalog-outputlen = 1800.
sl_fieldcatalog-intlen = 1800.
sl_fieldcatalog-dd_outlen = 1800.
ENDIF. "comm_plant
sl_fieldcatalog_new = sl_fieldcatalog.
APPEND sl_fieldcatalog_new TO tl_fieldcatalog_new.
APPEND sl_fieldcatalog-fieldname TO t_download_fieldname.
APPEND sl_fieldcatalog-scrtext_l TO t_download_fieldheading.
CLEAR: sl_fieldcatalog, sl_fieldcatalog_new.
ENDIF.
ENDIF.
ENDLOOP.
STEP: 3 - create dynamic internal table
FREE: ref_download.
CALL METHOD cl_alv_table_create=>create_dynamic_table
EXPORTING
I_STYLE_TABLE =
it_fieldcatalog = tl_fieldcatalog_new
IMPORTING
ep_table = ref_download
E_STYLE_FNAME =
EXCEPTIONS
generate_subpool_dir_full = 1
OTHERS = 2
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
ASSIGN ref_download->* TO <ft_download>.
CREATE DATA ref_wa LIKE LINE OF <ft_download>.
ASSIGN ref_wa->* TO <fs_download>.
STEP: 4 - populate data in dynamic internal table
LOOP AT t_outtab INTO wa_outtab.
LOOP AT t_download_fieldname.
ASSIGN COMPONENT t_download_fieldname OF STRUCTURE
<fs_download> TO <fs_download_field>.
IF t_download_fieldname-field EQ 'COMM_PLANT'.
STEP: 4.1 - get long text from database table
CLEAR: wal_table.
SELECT SINGLE * FROM zshaven_plnt_txt
INTO wal_table
WHERE vbeln = wa_outtab-vbeln
AND posnr = wa_outtab-posnr
AND del_no = wa_outtab-del_no
AND del_itm = wa_outtab-del_itm.
IF sy-subrc EQ 0.
STEP: 4.2 - break long-text into separate lines
CLEAR: tl_text. REFRESH: tl_text.
SPLIT wal_table-plant_comm
AT '~'
INTO TABLE tl_text.
STEP: 4.3 - Combine these separate lines with space in
between two lines
CLEAR: wal_text, final_text.
LOOP AT tl_text INTO wal_text.
IF final_text IS INITIAL.
final_text = wal_text.
ELSE.
CONCATENATE final_text '-' wal_text
INTO final_text.
REPLACE '-' WITH ' ' INTO final_text.
ENDIF.
ENDLOOP.
STEP: 4.4 - move long text to work-area
<fs_download_field> = final_text.
ENDIF. "subrc
ELSE. "t_download_fieldname
READ TABLE t_outtab_fieldname
WITH KEY field = t_download_fieldname-field.
ASSIGN COMPONENT t_outtab_fieldname-field OF STRUCTURE
wa_outtab TO <fs_outtab_field>.
<fs_download_field> = <fs_outtab_field>.
ENDIF.
ENDLOOP.
STEP: 4.5 - Move data from work-area to dynamic internal table
APPEND <fs_download> TO <ft_download>.
CLEAR: <fs_download>.
ENDLOOP.
STEP: 5 - download
CALL FUNCTION 'DOWNLOAD'
EXPORTING
filename = 'C:\zshaven.xls'
filetype = 'DAT'
filetype_no_show = 'X'
filetype_no_change = 'X'
TABLES
data_tab = <ft_download>
fieldnames = t_download_fieldheading
EXCEPTIONS
invalid_filesize = 1
invalid_table_width = 2
invalid_type = 3
no_batch = 4
unknown_error = 5
gui_refuse_filetransfer = 6
customer_error = 7
OTHERS = 8.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.