ABAP Select data from SAP table B021 into internal table

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Below is a number of ABAP code snippets to demonstrate how to select data from SAP B021 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 B021. 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 B021 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_B021 TYPE STANDARD TABLE OF B021,
      WA_B021 TYPE B021,
      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: <B021> TYPE B021.

*Process all fields in table header/work area as string values
  PERFORM process_as_string_field_values CHANGING wa_B021.

SELECT *
*restrict ABAP select to first 10 rows
 UP TO 10 ROWS      
  FROM B021
  INTO TABLE IT_B021.

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM B021
*  INTO TABLE @DATA(IT_B0212).
*--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_B021 INDEX 1 INTO DATA(WA_B0212).


*Demonstrate how to loop at an internal table and update values using a FIELD-SYMBOL
LOOP AT IT_B021 ASSIGNING <B021>.

*To update a field value using a field symbol simply change the value via the field symbol pointer
<B021>-MANDT = 1.
<B021>-KAPPL = 1.
<B021>-KSCHL = 1.
<B021>-LFART = 1.
<B021>-VSTEL = 1.

ENDLOOP.

LOOP AT IT_B021 INTO WA_B021.
*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_B021-KNUMH, sy-vline,
ENDLOOP.
   
*Add any further fields from structure WA_B021 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_B021 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_B021 INTO WA_B021.


*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_B021_STR, 
MANDT TYPE STRING,
KAPPL TYPE STRING,
KSCHL TYPE STRING,
LFART TYPE STRING,
VSTEL TYPE STRING,
KNUMH TYPE STRING,END OF T_EKKO_STR.
DATA: WA_B021_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_B021_STR-MANDT sy-vline 
WA_B021_STR-KAPPL sy-vline 
WA_B021_STR-KSCHL sy-vline 
WA_B021_STR-LFART sy-vline 
WA_B021_STR-VSTEL sy-vline 
WA_B021_STR-KNUMH sy-vline      INTO ld_text SEPARATED BY SPACE.

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