ABAP Select data from SAP table CNVFIELDS into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM CNVFIELDS
*  INTO TABLE @DATA(IT_CNVFIELDS2).
*--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_CNVFIELDS INDEX 1 INTO DATA(WA_CNVFIELDS2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<CNVFIELDS>-MANDT = 1.
<CNVFIELDS>-PACKID = 1.
<CNVFIELDS>-TABNAME = 1.
<CNVFIELDS>-FIELDNAME = 1.
<CNVFIELDS>-GRPFIELDS = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_CNVFIELDS-READONLY, sy-vline,
  WA_CNVFIELDS-CONVTYPE, sy-vline,
  WA_CNVFIELDS-CONVFUNC, sy-vline,
  WA_CNVFIELDS-CONVPROG, sy-vline,
  WA_CNVFIELDS-PRIORITY, sy-vline,
  WA_CNVFIELDS-SEQNUM, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_CNVFIELDS 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_CNVFIELDS 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_CNVFIELDS INTO WA_CNVFIELDS.


*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_CNVFIELDS_STR, 
MANDT TYPE STRING,
PACKID TYPE STRING,
TABNAME TYPE STRING,
FIELDNAME TYPE STRING,
GRPFIELDS TYPE STRING,
READONLY TYPE STRING,
CONVTYPE TYPE STRING,
CONVFUNC TYPE STRING,
CONVPROG TYPE STRING,
PRIORITY TYPE STRING,
SEQNUM TYPE STRING,
NOTUSE TYPE STRING,
PACKID_SRC TYPE STRING,
MCPOS TYPE STRING,
AGGREGATE TYPE STRING,
NODATA TYPE STRING,
CREATED TYPE STRING,
CRDATE TYPE STRING,
CRTIME TYPE STRING,
CRUSER TYPE STRING,
CHANGED TYPE STRING,
CHDATE TYPE STRING,
CHTIME TYPE STRING,
CHUSER TYPE STRING,
SOURCE TYPE STRING,
NONTRFIELD TYPE STRING,
NOMAPPING TYPE STRING,END OF T_EKKO_STR.
DATA: WA_CNVFIELDS_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_CNVFIELDS_STR-MANDT sy-vline 
WA_CNVFIELDS_STR-PACKID sy-vline 
WA_CNVFIELDS_STR-TABNAME sy-vline 
WA_CNVFIELDS_STR-FIELDNAME sy-vline 
WA_CNVFIELDS_STR-GRPFIELDS sy-vline 
WA_CNVFIELDS_STR-READONLY sy-vline 
WA_CNVFIELDS_STR-CONVTYPE sy-vline 
WA_CNVFIELDS_STR-CONVFUNC sy-vline 
WA_CNVFIELDS_STR-CONVPROG sy-vline 
WA_CNVFIELDS_STR-PRIORITY sy-vline 
WA_CNVFIELDS_STR-SEQNUM sy-vline 
WA_CNVFIELDS_STR-NOTUSE sy-vline 
WA_CNVFIELDS_STR-PACKID_SRC sy-vline 
WA_CNVFIELDS_STR-MCPOS sy-vline 
WA_CNVFIELDS_STR-AGGREGATE sy-vline 
WA_CNVFIELDS_STR-NODATA sy-vline 
WA_CNVFIELDS_STR-CREATED sy-vline 
WA_CNVFIELDS_STR-CRDATE sy-vline 
WA_CNVFIELDS_STR-CRTIME sy-vline 
WA_CNVFIELDS_STR-CRUSER sy-vline 
WA_CNVFIELDS_STR-CHANGED sy-vline 
WA_CNVFIELDS_STR-CHDATE sy-vline 
WA_CNVFIELDS_STR-CHTIME sy-vline 
WA_CNVFIELDS_STR-CHUSER sy-vline 
WA_CNVFIELDS_STR-SOURCE sy-vline 
WA_CNVFIELDS_STR-NONTRFIELD sy-vline 
WA_CNVFIELDS_STR-NOMAPPING sy-vline      INTO ld_text SEPARATED BY SPACE.

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