ABAP Select data from SAP table CAT_FDATA into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM CAT_FDATA
*  INTO TABLE @DATA(IT_CAT_FDATA2).
*--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_CAT_FDATA INDEX 1 INTO DATA(WA_CAT_FDATA2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<CAT_FDATA>-ABLNR = 1.
<CAT_FDATA>-COMMID = 1.
<CAT_FDATA>-SUBID = 1.
<CAT_FDATA>-CALLNO = 1.
<CAT_FDATA>-DELTA = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_CAT_FDATA-MODIFNO, sy-vline,
  WA_CAT_FDATA-COL_ID, sy-vline,
  WA_CAT_FDATA-ROW_ID, sy-vline,
  WA_CAT_FDATA-SUB_ROW_ID, sy-vline,
  WA_CAT_FDATA-VALUE, sy-vline,
ENDLOOP.
   
*Add any further fields from structure WA_CAT_FDATA 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_CAT_FDATA 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_CAT_FDATA INTO WA_CAT_FDATA.


*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_CAT_FDATA_STR, 
ABLNR TYPE STRING,
COMMID TYPE STRING,
SUBID TYPE STRING,
CALLNO TYPE STRING,
DELTA TYPE STRING,
MODIFNO TYPE STRING,
COL_ID TYPE STRING,
ROW_ID TYPE STRING,
SUB_ROW_ID TYPE STRING,
VALUE TYPE STRING,END OF T_EKKO_STR.
DATA: WA_CAT_FDATA_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_CAT_FDATA_STR-ABLNR sy-vline 
WA_CAT_FDATA_STR-COMMID sy-vline 
WA_CAT_FDATA_STR-SUBID sy-vline 
WA_CAT_FDATA_STR-CALLNO sy-vline 
WA_CAT_FDATA_STR-DELTA sy-vline 
WA_CAT_FDATA_STR-MODIFNO sy-vline 
WA_CAT_FDATA_STR-COL_ID sy-vline 
WA_CAT_FDATA_STR-ROW_ID sy-vline 
WA_CAT_FDATA_STR-SUB_ROW_ID sy-vline 
WA_CAT_FDATA_STR-VALUE sy-vline      INTO ld_text SEPARATED BY SPACE.

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