ABAP Select data from SAP table MDST into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM MDST
*  INTO TABLE @DATA(IT_MDST2).
*--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_MDST INDEX 1 INTO DATA(WA_MDST2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<MDST>-ANZEI = 1.
<MDST>-PRAST = 1.
<MDST>-KZSUM = 1.
<MDST>-INPER = 1.
<MDST>-MRPPP = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_MDST-ABKZG, sy-vline,
  WA_MDST-TRKZG, sy-vline,
  WA_MDST-VRFWE, sy-vline,
  WA_MDST-BEDVL, sy-vline,
  WA_MDST-KZATP, sy-vline,
  WA_MDST-KZUMT, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_MDST 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_MDST 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_MDST INTO WA_MDST.


*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 CUNIT, internal->external for field MEINH
CALL FUNCTION 'CONVERSION_EXIT_CUNIT_OUTPUT'
  EXPORTING
    input =                      WA_MDST-MEINH
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MDST-MEINH.
WRITE:/ 'New Value:', ld_input.

*Conversion exit CUNIT, internal->external for field WRKME
CALL FUNCTION 'CONVERSION_EXIT_CUNIT_OUTPUT'
  EXPORTING
    input =                      WA_MDST-WRKME
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MDST-WRKME.
WRITE:/ 'New Value:', ld_input.

*Conversion exit CUNIT, internal->external for field MEINH2
CALL FUNCTION 'CONVERSION_EXIT_CUNIT_OUTPUT'
  EXPORTING
    input =                      WA_MDST-MEINH2
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MDST-MEINH2.
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_MDST_STR, 
ANZEI TYPE STRING,
PRAST TYPE STRING,
KZSUM TYPE STRING,
INPER TYPE STRING,
MRPPP TYPE STRING,
ABKZG TYPE STRING,
TRKZG TYPE STRING,
VRFWE TYPE STRING,
BEDVL TYPE STRING,
KZATP TYPE STRING,
KZUMT TYPE STRING,
XLINE TYPE STRING,
SBZKZ TYPE STRING,
MEINH TYPE STRING,
GROKO TYPE STRING,
LIANZ TYPE STRING,
KUANZ TYPE STRING,
UEX1A TYPE STRING,
UEX2A TYPE STRING,
UEX3A TYPE STRING,
UX1PA TYPE STRING,
UX2PA TYPE STRING,
UX3PA TYPE STRING,
KDSRT TYPE STRING,
WIRKS TYPE STRING,
WRKME TYPE STRING,
WIRAK TYPE STRING,
WIRKF4 TYPE STRING,
MEINH2 TYPE STRING,
SMEKZ TYPE STRING,
WZFLG TYPE STRING,
MTREE TYPE STRING,
ATREE TYPE STRING,
DFILT TYPE STRING,
NAVPR TYPE STRING,
PRREG TYPE STRING,
ERGBZ TYPE STRING,
FILBZ TYPE STRING,
TREET TYPE STRING,
KZMKA TYPE STRING,
MEMFL TYPE STRING,
ORDPR TYPE STRING,
MDATS TYPE STRING,
MDNVM TYPE STRING,
MDKUM TYPE STRING,
MDSEPDB TYPE STRING,
MDZGD TYPE STRING,
ADPIC_NO_AGGR TYPE STRING,END OF T_EKKO_STR.
DATA: WA_MDST_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_MDST_STR-ANZEI sy-vline 
WA_MDST_STR-PRAST sy-vline 
WA_MDST_STR-KZSUM sy-vline 
WA_MDST_STR-INPER sy-vline 
WA_MDST_STR-MRPPP sy-vline 
WA_MDST_STR-ABKZG sy-vline 
WA_MDST_STR-TRKZG sy-vline 
WA_MDST_STR-VRFWE sy-vline 
WA_MDST_STR-BEDVL sy-vline 
WA_MDST_STR-KZATP sy-vline 
WA_MDST_STR-KZUMT sy-vline 
WA_MDST_STR-XLINE sy-vline 
WA_MDST_STR-SBZKZ sy-vline 
WA_MDST_STR-MEINH sy-vline 
WA_MDST_STR-GROKO sy-vline 
WA_MDST_STR-LIANZ sy-vline 
WA_MDST_STR-KUANZ sy-vline 
WA_MDST_STR-UEX1A sy-vline 
WA_MDST_STR-UEX2A sy-vline 
WA_MDST_STR-UEX3A sy-vline 
WA_MDST_STR-UX1PA sy-vline 
WA_MDST_STR-UX2PA sy-vline 
WA_MDST_STR-UX3PA sy-vline 
WA_MDST_STR-KDSRT sy-vline 
WA_MDST_STR-WIRKS sy-vline 
WA_MDST_STR-WRKME sy-vline 
WA_MDST_STR-WIRAK sy-vline 
WA_MDST_STR-WIRKF4 sy-vline 
WA_MDST_STR-MEINH2 sy-vline 
WA_MDST_STR-SMEKZ sy-vline 
WA_MDST_STR-WZFLG sy-vline 
WA_MDST_STR-MTREE sy-vline 
WA_MDST_STR-ATREE sy-vline 
WA_MDST_STR-DFILT sy-vline 
WA_MDST_STR-NAVPR sy-vline 
WA_MDST_STR-PRREG sy-vline 
WA_MDST_STR-ERGBZ sy-vline 
WA_MDST_STR-FILBZ sy-vline 
WA_MDST_STR-TREET sy-vline 
WA_MDST_STR-KZMKA sy-vline 
WA_MDST_STR-MEMFL sy-vline 
WA_MDST_STR-ORDPR sy-vline 
WA_MDST_STR-MDATS sy-vline 
WA_MDST_STR-MDNVM sy-vline 
WA_MDST_STR-MDKUM sy-vline 
WA_MDST_STR-MDSEPDB sy-vline 
WA_MDST_STR-MDZGD sy-vline 
WA_MDST_STR-ADPIC_NO_AGGR sy-vline      INTO ld_text SEPARATED BY SPACE.

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