ABAP Select data from SAP table SNIWEL3 into internal table

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Below is a number of ABAP code snippets to demonstrate how to select data from SAP SNIWEL3 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 SNIWEL3. 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 SNIWEL3 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_SNIWEL3 TYPE STANDARD TABLE OF SNIWEL3,
      WA_SNIWEL3 TYPE SNIWEL3,
      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: <SNIWEL3> TYPE SNIWEL3.

*Process all fields in table header/work area as string values
  PERFORM process_as_string_field_values CHANGING wa_SNIWEL3.

SELECT *
*restrict ABAP select to first 10 rows
 UP TO 10 ROWS      
  FROM SNIWEL3
  INTO TABLE IT_SNIWEL3.

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM SNIWEL3
*  INTO TABLE @DATA(IT_SNIWEL32).
*--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_SNIWEL3 INDEX 1 INTO DATA(WA_SNIWEL32).


*Demonstrate how to loop at an internal table and update values using a FIELD-SYMBOL
LOOP AT IT_SNIWEL3 ASSIGNING <SNIWEL3>.

*To update a field value using a field symbol simply change the value via the field symbol pointer
<SNIWEL3>-POLA1 = 1.
<SNIWEL3>-POLA2 = 1.
<SNIWEL3>-POLA3 = 1.
<SNIWEL3>-BUPO1 = 1.
<SNIWEL3>-BUPO2 = 1.

ENDLOOP.

LOOP AT IT_SNIWEL3 INTO WA_SNIWEL3.
*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_SNIWEL3-BUKA1, sy-vline,
  WA_SNIWEL3-BUKA2, sy-vline,
  WA_SNIWEL3-BUKA3, sy-vline,
  WA_SNIWEL3-RULA1, sy-vline,
  WA_SNIWEL3-RULA2, sy-vline,
  WA_SNIWEL3-RULA3, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_SNIWEL3 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_SNIWEL3 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_SNIWEL3 INTO WA_SNIWEL3.


*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_SNIWEL3_STR, 
POLA1 TYPE STRING,
POLA2 TYPE STRING,
POLA3 TYPE STRING,
BUPO1 TYPE STRING,
BUPO2 TYPE STRING,
BUKA1 TYPE STRING,
BUKA2 TYPE STRING,
BUKA3 TYPE STRING,
RULA1 TYPE STRING,
RULA2 TYPE STRING,
RULA3 TYPE STRING,END OF T_EKKO_STR.
DATA: WA_SNIWEL3_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_SNIWEL3_STR-POLA1 sy-vline 
WA_SNIWEL3_STR-POLA2 sy-vline 
WA_SNIWEL3_STR-POLA3 sy-vline 
WA_SNIWEL3_STR-BUPO1 sy-vline 
WA_SNIWEL3_STR-BUPO2 sy-vline 
WA_SNIWEL3_STR-BUKA1 sy-vline 
WA_SNIWEL3_STR-BUKA2 sy-vline 
WA_SNIWEL3_STR-BUKA3 sy-vline 
WA_SNIWEL3_STR-RULA1 sy-vline 
WA_SNIWEL3_STR-RULA2 sy-vline 
WA_SNIWEL3_STR-RULA3 sy-vline      INTO ld_text SEPARATED BY SPACE.

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