ABAP Select data from SAP table TN21S into internal table

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Below is a number of ABAP code snippets to demonstrate how to select data from SAP TN21S 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 TN21S. 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 TN21S 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_TN21S TYPE STANDARD TABLE OF TN21S,
      WA_TN21S TYPE TN21S,
      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: <TN21S> TYPE TN21S.

*Process all fields in table header/work area as string values
  PERFORM process_as_string_field_values CHANGING wa_TN21S.

SELECT *
*restrict ABAP select to first 10 rows
 UP TO 10 ROWS      
  FROM TN21S
  INTO TABLE IT_TN21S.

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM TN21S
*  INTO TABLE @DATA(IT_TN21S2).
*--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_TN21S INDEX 1 INTO DATA(WA_TN21S2).


*Demonstrate how to loop at an internal table and update values using a FIELD-SYMBOL
LOOP AT IT_TN21S ASSIGNING <TN21S>.

*To update a field value using a field symbol simply change the value via the field symbol pointer
<TN21S>-MANDT = 1.
<TN21S>-EINRI = 1.
<TN21S>-AAPSI = 1.
<TN21S>-AAPSS = 1.
<TN21S>-MSGTY = 1.

ENDLOOP.

LOOP AT IT_TN21S INTO WA_TN21S.
*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_TN21S-SELST, sy-vline,
  WA_TN21S-SELTX, sy-vline,
  WA_TN21S-SUMRE, sy-vline,
  WA_TN21S-FKDATN, sy-vline,
  WA_TN21S-PERSP, sy-vline,
  WA_TN21S-REVASGN, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_TN21S 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_TN21S 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_TN21S INTO WA_TN21S.


*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 EINRI
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_TN21S-EINRI
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_TN21S-EINRI.
WRITE:/ 'New Value:', ld_input.

*Conversion exit ALPHA, internal->external for field SELST
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_TN21S-SELST
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_TN21S-SELST.
WRITE:/ 'New Value:', ld_input.

*Conversion exit ALPHA, internal->external for field DFORM
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_TN21S-DFORM
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_TN21S-DFORM.
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_TN21S_STR, 
MANDT TYPE STRING,
EINRI TYPE STRING,
AAPSI TYPE STRING,
AAPSS TYPE STRING,
MSGTY TYPE STRING,
SELST TYPE STRING,
SELTX TYPE STRING,
SUMRE TYPE STRING,
FKDATN TYPE STRING,
PERSP TYPE STRING,
REVASGN TYPE STRING,
CANPRS TYPE STRING,
CANNPS TYPE STRING,
PDNET TYPE STRING,
PDGRO TYPE STRING,
DFORM TYPE STRING,
OPTDAT TYPE STRING,
PSYCHOPTDAT TYPE STRING,
TIBIL TYPE STRING,END OF T_EKKO_STR.
DATA: WA_TN21S_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_TN21S_STR-MANDT sy-vline 
WA_TN21S_STR-EINRI sy-vline 
WA_TN21S_STR-AAPSI sy-vline 
WA_TN21S_STR-AAPSS sy-vline 
WA_TN21S_STR-MSGTY sy-vline 
WA_TN21S_STR-SELST sy-vline 
WA_TN21S_STR-SELTX sy-vline 
WA_TN21S_STR-SUMRE sy-vline 
WA_TN21S_STR-FKDATN sy-vline 
WA_TN21S_STR-PERSP sy-vline 
WA_TN21S_STR-REVASGN sy-vline 
WA_TN21S_STR-CANPRS sy-vline 
WA_TN21S_STR-CANNPS sy-vline 
WA_TN21S_STR-PDNET sy-vline 
WA_TN21S_STR-PDGRO sy-vline 
WA_TN21S_STR-DFORM sy-vline 
WA_TN21S_STR-OPTDAT sy-vline 
WA_TN21S_STR-PSYCHOPTDAT sy-vline 
WA_TN21S_STR-TIBIL sy-vline      INTO ld_text SEPARATED BY SPACE.

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