ABAP Select data from SAP table MDALV_LISTREQUIREMENTS into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM MDALV_LISTREQUIREMENTS
*  INTO TABLE @DATA(IT_MDALV_LISTREQUIREMENTS2).
*--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_MDALV_LISTREQUIREMENTS INDEX 1 INTO DATA(WA_MDALV_LISTREQUIREMENTS2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<MDALV_LISTREQUIREMENTS>-MATNR = 1.
<MDALV_LISTREQUIREMENTS>-MAKTX = 1.
<MDALV_LISTREQUIREMENTS>-WERKS = 1.
<MDALV_LISTREQUIREMENTS>-WERKS = 1.
<MDALV_LISTREQUIREMENTS>-BEDAE = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_MDALV_LISTREQUIREMENTS-VERSB, sy-vline,
  WA_MDALV_LISTREQUIREMENTS-PBDNR, sy-vline,
  WA_MDALV_LISTREQUIREMENTS-VERVS, sy-vline,
  WA_MDALV_LISTREQUIREMENTS-DATUV, sy-vline,
  WA_MDALV_LISTREQUIREMENTS-DATUB, sy-vline,
  WA_MDALV_LISTREQUIREMENTS-BDZEI, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_MDALV_LISTREQUIREMENTS 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_MDALV_LISTREQUIREMENTS 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_MDALV_LISTREQUIREMENTS INTO WA_MDALV_LISTREQUIREMENTS.


*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.

*Conversion exit MATN1, internal->external for field MATNR
CALL FUNCTION 'CONVERSION_EXIT_MATN1_OUTPUT'
  EXPORTING
    input =                      WA_MDALV_LISTREQUIREMENTS-MATNR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MDALV_LISTREQUIREMENTS-MATNR.
WRITE:/ 'New Value:', ld_input.
ENDFORM. 

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

TYPES: BEGIN OF T_MDALV_LISTREQUIREMENTS_STR, 
MATNR TYPE STRING,
MAKTX TYPE STRING,
WERKS TYPE STRING,
WERKS TYPE STRING,
BEDAE TYPE STRING,
VERSB TYPE STRING,
PBDNR TYPE STRING,
VERVS TYPE STRING,
DATUV TYPE STRING,
DATUB TYPE STRING,
BDZEI TYPE STRING,END OF T_EKKO_STR.
DATA: WA_MDALV_LISTREQUIREMENTS_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_MDALV_LISTREQUIREMENTS_STR-MATNR sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-MAKTX sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-WERKS sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-WERKS sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-BEDAE sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-VERSB sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-PBDNR sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-VERVS sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-DATUV sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-DATUB sy-vline 
WA_MDALV_LISTREQUIREMENTS_STR-BDZEI sy-vline      INTO ld_text SEPARATED BY SPACE.

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