ABAP Select data from SAP table WVERALV_MSEG into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM WVERALV_MSEG
*  INTO TABLE @DATA(IT_WVERALV_MSEG2).
*--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_WVERALV_MSEG INDEX 1 INTO DATA(WA_WVERALV_MSEG2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<WVERALV_MSEG>-MATNR = 1.
<WVERALV_MSEG>-WERKS = 1.
<WVERALV_MSEG>-LGORT = 1.
<WVERALV_MSEG>-CHARG = 1.
<WVERALV_MSEG>-ERFMG = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_WVERALV_MSEG-ERFME, sy-vline,
  WA_WVERALV_MSEG-BEAKZ, sy-vline,
  WA_WVERALV_MSEG-ID, sy-vline,
  WA_WVERALV_MSEG-MSGID, sy-vline,
  WA_WVERALV_MSEG-MSGNO, sy-vline,
  WA_WVERALV_MSEG-MSGTX, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_WVERALV_MSEG 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_WVERALV_MSEG 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_WVERALV_MSEG INTO WA_WVERALV_MSEG.


*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_WVERALV_MSEG-MATNR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_WVERALV_MSEG-MATNR.
WRITE:/ 'New Value:', ld_input.

*Conversion exit CUNIT, internal->external for field ERFME
CALL FUNCTION 'CONVERSION_EXIT_CUNIT_OUTPUT'
  EXPORTING
    input =                      WA_WVERALV_MSEG-ERFME
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_WVERALV_MSEG-ERFME.
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_WVERALV_MSEG_STR, 
MATNR TYPE STRING,
WERKS TYPE STRING,
LGORT TYPE STRING,
CHARG TYPE STRING,
ERFMG TYPE STRING,
ERFME TYPE STRING,
BEAKZ TYPE STRING,
ID TYPE STRING,
MSGID TYPE STRING,
MSGNO TYPE STRING,
MSGTX TYPE STRING,
MSGTY TYPE STRING,END OF T_EKKO_STR.
DATA: WA_WVERALV_MSEG_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_WVERALV_MSEG_STR-MATNR sy-vline 
WA_WVERALV_MSEG_STR-WERKS sy-vline 
WA_WVERALV_MSEG_STR-LGORT sy-vline 
WA_WVERALV_MSEG_STR-CHARG sy-vline 
WA_WVERALV_MSEG_STR-ERFMG sy-vline 
WA_WVERALV_MSEG_STR-ERFME sy-vline 
WA_WVERALV_MSEG_STR-BEAKZ sy-vline 
WA_WVERALV_MSEG_STR-ID sy-vline 
WA_WVERALV_MSEG_STR-MSGID sy-vline 
WA_WVERALV_MSEG_STR-MSGNO sy-vline 
WA_WVERALV_MSEG_STR-MSGTX sy-vline 
WA_WVERALV_MSEG_STR-MSGTY sy-vline      INTO ld_text SEPARATED BY SPACE.

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