ABAP Select data from SAP table LREFN into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM LREFN
*  INTO TABLE @DATA(IT_LREFN2).
*--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_LREFN INDEX 1 INTO DATA(WA_LREFN2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<LREFN>-MANDT = 1.
<LREFN>-LGNUM = 1.
<LREFN>-REFNR = 1.
<LREFN>-REFNT = 1.
<LREFN>-RBTYP = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_LREFN-KZSPE, sy-vline,
  WA_LREFN-KZAKT, sy-vline,
  WA_LREFN-KZDRU, sy-vline,
  WA_LREFN-DATUM, sy-vline,
  WA_LREFN-DRUKZ, sy-vline,
  WA_LREFN-LDEST, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_LREFN 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_LREFN 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_LREFN INTO WA_LREFN.


*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 REFNR
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_LREFN-REFNR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_LREFN-REFNR.
WRITE:/ 'New Value:', ld_input.

*Conversion exit SPDEV, internal->external for field LDEST
CALL FUNCTION 'CONVERSION_EXIT_SPDEV_OUTPUT'
  EXPORTING
    input =                      WA_LREFN-LDEST
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_LREFN-LDEST.
WRITE:/ 'New Value:', ld_input.

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

*Conversion exit TSHME, internal->external for field RLSDT
CALL FUNCTION 'CONVERSION_EXIT_TSHME_OUTPUT'
  EXPORTING
    input =                      WA_LREFN-RLSDT
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_LREFN-RLSDT.
WRITE:/ 'New Value:', ld_input.

*Conversion exit TSHME, internal->external for field LRLSD
CALL FUNCTION 'CONVERSION_EXIT_TSHME_OUTPUT'
  EXPORTING
    input =                      WA_LREFN-LRLSD
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_LREFN-LRLSD.
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_LREFN_STR, 
MANDT TYPE STRING,
LGNUM TYPE STRING,
REFNR TYPE STRING,
REFNT TYPE STRING,
RBTYP TYPE STRING,
KZSPE TYPE STRING,
KZAKT TYPE STRING,
KZDRU TYPE STRING,
DATUM TYPE STRING,
DRUKZ TYPE STRING,
LDEST TYPE STRING,
DRDAT TYPE STRING,
KZKOM TYPE STRING,
KZERL TYPE STRING,
SAMMG TYPE STRING,
KWPRO TYPE STRING,
KAPTP TYPE STRING,
L2SKR TYPE STRING,
L2SKM TYPE STRING,
L2SKP TYPE STRING,
TRART TYPE STRING,
CDSTO TYPE STRING,
RLSDT TYPE STRING,
LRLSD TYPE STRING,
FTEXT TYPE STRING,
AUFTE TYPE STRING,
DIREK TYPE STRING,
ENTNA TYPE STRING,
AUFDR TYPE STRING,
DIRDR TYPE STRING,
ENTDR TYPE STRING,END OF T_EKKO_STR.
DATA: WA_LREFN_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_LREFN_STR-MANDT sy-vline 
WA_LREFN_STR-LGNUM sy-vline 
WA_LREFN_STR-REFNR sy-vline 
WA_LREFN_STR-REFNT sy-vline 
WA_LREFN_STR-RBTYP sy-vline 
WA_LREFN_STR-KZSPE sy-vline 
WA_LREFN_STR-KZAKT sy-vline 
WA_LREFN_STR-KZDRU sy-vline 
WA_LREFN_STR-DATUM sy-vline 
WA_LREFN_STR-DRUKZ sy-vline 
WA_LREFN_STR-LDEST sy-vline 
WA_LREFN_STR-DRDAT sy-vline 
WA_LREFN_STR-KZKOM sy-vline 
WA_LREFN_STR-KZERL sy-vline 
WA_LREFN_STR-SAMMG sy-vline 
WA_LREFN_STR-KWPRO sy-vline 
WA_LREFN_STR-KAPTP sy-vline 
WA_LREFN_STR-L2SKR sy-vline 
WA_LREFN_STR-L2SKM sy-vline 
WA_LREFN_STR-L2SKP sy-vline 
WA_LREFN_STR-TRART sy-vline 
WA_LREFN_STR-CDSTO sy-vline 
WA_LREFN_STR-RLSDT sy-vline 
WA_LREFN_STR-LRLSD sy-vline 
WA_LREFN_STR-FTEXT sy-vline 
WA_LREFN_STR-AUFTE sy-vline 
WA_LREFN_STR-DIREK sy-vline 
WA_LREFN_STR-ENTNA sy-vline 
WA_LREFN_STR-AUFDR sy-vline 
WA_LREFN_STR-DIRDR sy-vline 
WA_LREFN_STR-ENTDR sy-vline      INTO ld_text SEPARATED BY SPACE.

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