ABAP Select data from SAP table LIST_WG into internal table

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Below is a number of ABAP code snippets to demonstrate how to select data from SAP LIST_WG table and store it within an internal table, including using the newer @DATA inline declaration methods. It also shows you various ways to process this data using ABAP work area, inline declaration or field symbols including executing all the relevant CONVERSION_EXIT routines specific to LIST_WG. See here for more generic Select statement tips.

Sometimes data within SAP is stored within the database table in a different format to what it is displayed to the user. These input/output conversation FM routines are what translates the data between the two formats.

There is also a full declaration of the LIST_WG table where each field has a char/string type for you to simply copy and paste. This allows you to use processing that is only available to these field types such as the CONCATENATE statement.

DATA: IT_LIST_WG TYPE STANDARD TABLE OF LIST_WG,
      WA_LIST_WG TYPE LIST_WG,
      GD_STR TYPE STRING.

DATA: lo_typedescr type REF TO cl_abap_typedescr.
DATA: lv_fieldname type fieldname.

FIELD-SYMBOLS: <FIELD> TYPE any.
FIELD-SYMBOLS: <LIST_WG> TYPE LIST_WG.

*Process all fields in table header/work area as string values
  PERFORM process_as_string_field_values CHANGING wa_LIST_WG.

SELECT *
*restrict ABAP select to first 10 rows
 UP TO 10 ROWS      
  FROM LIST_WG
  INTO TABLE IT_LIST_WG.

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM LIST_WG
*  INTO TABLE @DATA(IT_LIST_WG2).
*--Further methods of using ABAP code to  select data from SAP database tables

*You can also declare the header/work area using the in-line DATA declaration method
READ TABLE IT_LIST_WG INDEX 1 INTO DATA(WA_LIST_WG2).


*Demonstrate how to loop at an internal table and update values using a FIELD-SYMBOL
LOOP AT IT_LIST_WG ASSIGNING <LIST_WG>.

*To update a field value using a field symbol simply change the value via the field symbol pointer
<LIST_WG>-APPLEXT = 1.
<LIST_WG>-PAGENAME = 1.
<LIST_WG>-DEVCLASS = 1.
<LIST_WG>-AUTHOR = 1.
<LIST_WG>-CREATEDON = 1.

ENDLOOP.

LOOP AT IT_LIST_WG INTO WA_LIST_WG.
*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_LIST_WG-CHANGEDBY, sy-vline,
  WA_LIST_WG-CHANGEDON, sy-vline,
  WA_LIST_WG-SECUREHTTP, sy-vline,
  WA_LIST_WG-LIFETIME, sy-vline,
  WA_LIST_WG-CHANGETIME, sy-vline,
ENDLOOP.
   
*Add any further fields from structure WA_LIST_WG you want to display...

  WRITE:/ sy-uline.
* Aternatively use generic code to Write field values (and NAME) to screen report
  DO.
    ASSIGN COMPONENT sy-index OF STRUCTURE wa_LIST_WG TO <field>.
    IF sy-subrc <> 0. EXIT. ENDIF.
    WRITE:/ 'Field Value', <field>, sy-vline.
    gd_str = <field> .
    lo_typedescr ?= CL_ABAP_DATADESCR=>DESCRIBE_BY_DATA( <field> ).
    lv_fieldname = lo_typedescr->GET_RELATIVE_NAME( ).
    WRITE:/ 'Field Name', lv_fieldname.
  ENDDO.

  
*Redo loop but convert all fields from internal to out value  
LOOP AT IT_LIST_WG INTO WA_LIST_WG.


*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Convert all fields to display/output versions using conversion routines
  PERFORM convert_all_field_values CHANGING wa_EKKO.
	 
ENDLOOP.

  
*&---------------------------------------------------------------------*
*& Form convert_all_field_values
*&---------------------------------------------------------------------*
FORM convert_all_field_values CHANGING p_EKKO LIKE wa_EKKO.
DATA: ld_input(1000) TYPE c, ld_output(1000) TYPE C.
ENDFORM. 

*&---------------------------------------------------------------------*
*& Form process_as_string_field_values
*&---------------------------------------------------------------------*
FORM process_as_string_field_values CHANGING p_EKKO LIKE wa_EKKO.

TYPES: BEGIN OF T_LIST_WG_STR, 
APPLEXT TYPE STRING,
PAGENAME TYPE STRING,
DEVCLASS TYPE STRING,
AUTHOR TYPE STRING,
CREATEDON TYPE STRING,
CHANGEDBY TYPE STRING,
CHANGEDON TYPE STRING,
SECUREHTTP TYPE STRING,
LIFETIME TYPE STRING,
CHANGETIME TYPE STRING,END OF T_EKKO_STR.
DATA: WA_LIST_WG_STR type T_EKKO_STR.

DATA: ld_text TYPE string.

LOOP AT IT_EKKO INTO WA_EKKO.
  MOVE-CORRESPONDING wa_EKKO TO WA_EKKO_STR.
  CONCATENATE: sy-vline
WA_LIST_WG_STR-APPLEXT sy-vline 
WA_LIST_WG_STR-PAGENAME sy-vline 
WA_LIST_WG_STR-DEVCLASS sy-vline 
WA_LIST_WG_STR-AUTHOR sy-vline 
WA_LIST_WG_STR-CREATEDON sy-vline 
WA_LIST_WG_STR-CHANGEDBY sy-vline 
WA_LIST_WG_STR-CHANGEDON sy-vline 
WA_LIST_WG_STR-SECUREHTTP sy-vline 
WA_LIST_WG_STR-LIFETIME sy-vline 
WA_LIST_WG_STR-CHANGETIME sy-vline      INTO ld_text SEPARATED BY SPACE.

*Add any further fields from structure WA_EKKO_STR you want to CONCATENATE...
ENDLOOP.
ENDFORM.