ABAP Select data from SAP table J_1AMSGMM into internal table

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Below is a number of ABAP code snippets to demonstrate how to select data from SAP J_1AMSGMM 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 J_1AMSGMM. 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 J_1AMSGMM 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_J_1AMSGMM TYPE STANDARD TABLE OF J_1AMSGMM,
      WA_J_1AMSGMM TYPE J_1AMSGMM,
      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: <J_1AMSGMM> TYPE J_1AMSGMM.

*Process all fields in table header/work area as string values
  PERFORM process_as_string_field_values CHANGING wa_J_1AMSGMM.

SELECT *
*restrict ABAP select to first 10 rows
 UP TO 10 ROWS      
  FROM J_1AMSGMM
  INTO TABLE IT_J_1AMSGMM.

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM J_1AMSGMM
*  INTO TABLE @DATA(IT_J_1AMSGMM2).
*--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_J_1AMSGMM INDEX 1 INTO DATA(WA_J_1AMSGMM2).


*Demonstrate how to loop at an internal table and update values using a FIELD-SYMBOL
LOOP AT IT_J_1AMSGMM ASSIGNING <J_1AMSGMM>.

*To update a field value using a field symbol simply change the value via the field symbol pointer
<J_1AMSGMM>-MSGV1 = 1.
<J_1AMSGMM>-MSGV2 = 1.
<J_1AMSGMM>-MSGV3 = 1.
<J_1AMSGMM>-MSGV4 = 1.
<J_1AMSGMM>-MSGV5 = 1.

ENDLOOP.

LOOP AT IT_J_1AMSGMM INTO WA_J_1AMSGMM.
*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_J_1AMSGMM-MSGTY, sy-vline,
  WA_J_1AMSGMM-MSGID, sy-vline,
  WA_J_1AMSGMM-MSGNO, sy-vline,
  WA_J_1AMSGMM-MSSPC, sy-vline,
  WA_J_1AMSGMM-MSGTX, sy-vline,
ENDLOOP.
   
*Add any further fields from structure WA_J_1AMSGMM 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_J_1AMSGMM 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_J_1AMSGMM INTO WA_J_1AMSGMM.


*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.
ENDFORM. 

*&---------------------------------------------------------------------*
*& Form process_as_string_field_values
*&---------------------------------------------------------------------*
FORM process_as_string_field_values CHANGING p_EKKO LIKE wa_EKKO.

TYPES: BEGIN OF T_J_1AMSGMM_STR, 
MSGV1 TYPE STRING,
MSGV2 TYPE STRING,
MSGV3 TYPE STRING,
MSGV4 TYPE STRING,
MSGV5 TYPE STRING,
MSGTY TYPE STRING,
MSGID TYPE STRING,
MSGNO TYPE STRING,
MSSPC TYPE STRING,
MSGTX TYPE STRING,END OF T_EKKO_STR.
DATA: WA_J_1AMSGMM_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_J_1AMSGMM_STR-MSGV1 sy-vline 
WA_J_1AMSGMM_STR-MSGV2 sy-vline 
WA_J_1AMSGMM_STR-MSGV3 sy-vline 
WA_J_1AMSGMM_STR-MSGV4 sy-vline 
WA_J_1AMSGMM_STR-MSGV5 sy-vline 
WA_J_1AMSGMM_STR-MSGTY sy-vline 
WA_J_1AMSGMM_STR-MSGID sy-vline 
WA_J_1AMSGMM_STR-MSGNO sy-vline 
WA_J_1AMSGMM_STR-MSSPC sy-vline 
WA_J_1AMSGMM_STR-MSGTX sy-vline      INTO ld_text SEPARATED BY SPACE.

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