ABAP Select data from SAP table MLHD into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM MLHD
*  INTO TABLE @DATA(IT_MLHD2).
*--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_MLHD INDEX 1 INTO DATA(WA_MLHD2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<MLHD>-MANDT = 1.
<MLHD>-BELNR = 1.
<MLHD>-KJAHR = 1.
<MLHD>-VGART = 1.
<MLHD>-LDGRP = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_MLHD-AWTYP, sy-vline,
  WA_MLHD-AWREF, sy-vline,
  WA_MLHD-AWORG, sy-vline,
  WA_MLHD-AWSYS, sy-vline,
  WA_MLHD-STORNO, sy-vline,
  WA_MLHD-UMBEW, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_MLHD 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_MLHD 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_MLHD INTO WA_MLHD.


*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 ALPHA, internal->external for field BELNR
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_MLHD-BELNR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MLHD-BELNR.
WRITE:/ 'New Value:', ld_input.

*Conversion exit GJAHR, internal->external for field KJAHR
CALL FUNCTION 'CONVERSION_EXIT_GJAHR_OUTPUT'
  EXPORTING
    input =                      WA_MLHD-KJAHR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MLHD-KJAHR.
WRITE:/ 'New Value:', ld_input.

*Conversion exit ALPHA, internal->external for field AWREF
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_MLHD-AWREF
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MLHD-AWREF.
WRITE:/ 'New Value:', ld_input.

*Conversion exit ALPHA, internal->external for field AWSYS
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_MLHD-AWSYS
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MLHD-AWSYS.
WRITE:/ 'New Value:', ld_input.

*Conversion exit ALPHA, internal->external for field LOGSYS
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_MLHD-LOGSYS
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MLHD-LOGSYS.
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_MLHD_STR, 
MANDT TYPE STRING,
BELNR TYPE STRING,
KJAHR TYPE STRING,
VGART TYPE STRING,
LDGRP TYPE STRING,
AWTYP TYPE STRING,
AWREF TYPE STRING,
AWORG TYPE STRING,
AWSYS TYPE STRING,
STORNO TYPE STRING,
UMBEW TYPE STRING,
BLDAT TYPE STRING,
CPUDT TYPE STRING,
CPUTM TYPE STRING,
USNAM TYPE STRING,
TCODE TYPE STRING,
GLVOR TYPE STRING,
LOGSYS TYPE STRING,
PVERS TYPE STRING,
XCOBL_CONS TYPE STRING,
BKTXT TYPE STRING,
KONGR TYPE STRING,
ACC_PRINCIPLE TYPE STRING,END OF T_EKKO_STR.
DATA: WA_MLHD_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_MLHD_STR-MANDT sy-vline 
WA_MLHD_STR-BELNR sy-vline 
WA_MLHD_STR-KJAHR sy-vline 
WA_MLHD_STR-VGART sy-vline 
WA_MLHD_STR-LDGRP sy-vline 
WA_MLHD_STR-AWTYP sy-vline 
WA_MLHD_STR-AWREF sy-vline 
WA_MLHD_STR-AWORG sy-vline 
WA_MLHD_STR-AWSYS sy-vline 
WA_MLHD_STR-STORNO sy-vline 
WA_MLHD_STR-UMBEW sy-vline 
WA_MLHD_STR-BLDAT sy-vline 
WA_MLHD_STR-CPUDT sy-vline 
WA_MLHD_STR-CPUTM sy-vline 
WA_MLHD_STR-USNAM sy-vline 
WA_MLHD_STR-TCODE sy-vline 
WA_MLHD_STR-GLVOR sy-vline 
WA_MLHD_STR-LOGSYS sy-vline 
WA_MLHD_STR-PVERS sy-vline 
WA_MLHD_STR-XCOBL_CONS sy-vline 
WA_MLHD_STR-BKTXT sy-vline 
WA_MLHD_STR-KONGR sy-vline 
WA_MLHD_STR-ACC_PRINCIPLE sy-vline      INTO ld_text SEPARATED BY SPACE.

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