ABAP Select data from SAP table MDML into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM MDML
*  INTO TABLE @DATA(IT_MDML2).
*--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_MDML INDEX 1 INTO DATA(WA_MDML2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<MDML>-MATNR = 1.
<MDML>-WERKS = 1.
<MDML>-VERID = 1.
<MDML>-LINIE = 1.
<MDML>-LINHI = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_MDML-MDV02, sy-vline,
  WA_MDML-BDATU, sy-vline,
  WA_MDML-ADATU, sy-vline,
  WA_MDML-VERTO, sy-vline,
  WA_MDML-ALORT, sy-vline,
ENDLOOP.
   
*Add any further fields from structure WA_MDML 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_MDML 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_MDML INTO WA_MDML.


*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_MDML-MATNR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_MDML-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_MDML_STR, 
MATNR TYPE STRING,
WERKS TYPE STRING,
VERID TYPE STRING,
LINIE TYPE STRING,
LINHI TYPE STRING,
MDV02 TYPE STRING,
BDATU TYPE STRING,
ADATU TYPE STRING,
VERTO TYPE STRING,
ALORT TYPE STRING,END OF T_EKKO_STR.
DATA: WA_MDML_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_MDML_STR-MATNR sy-vline 
WA_MDML_STR-WERKS sy-vline 
WA_MDML_STR-VERID sy-vline 
WA_MDML_STR-LINIE sy-vline 
WA_MDML_STR-LINHI sy-vline 
WA_MDML_STR-MDV02 sy-vline 
WA_MDML_STR-BDATU sy-vline 
WA_MDML_STR-ADATU sy-vline 
WA_MDML_STR-VERTO sy-vline 
WA_MDML_STR-ALORT sy-vline      INTO ld_text SEPARATED BY SPACE.

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