ABAP Select data from SAP table A991 into internal table

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Below is a number of ABAP code snippets to demonstrate how to select data from SAP A991 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 A991. 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 A991 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_A991 TYPE STANDARD TABLE OF A991,
      WA_A991 TYPE A991,
      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: <A991> TYPE A991.

*Process all fields in table header/work area as string values
  PERFORM process_as_string_field_values CHANGING wa_A991.

SELECT *
*restrict ABAP select to first 10 rows
 UP TO 10 ROWS      
  FROM A991
  INTO TABLE IT_A991.

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM A991
*  INTO TABLE @DATA(IT_A9912).
*--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_A991 INDEX 1 INTO DATA(WA_A9912).


*Demonstrate how to loop at an internal table and update values using a FIELD-SYMBOL
LOOP AT IT_A991 ASSIGNING <A991>.

*To update a field value using a field symbol simply change the value via the field symbol pointer
<A991>-MANDT = 1.
<A991>-KAPPL = 1.
<A991>-KSCHL = 1.
<A991>-TDLNR = 1.
<A991>-LPRIO = 1.

ENDLOOP.

LOOP AT IT_A991 INTO WA_A991.
*Write horizonal line to screen report.
  WRITE:/ sy-uline.

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_A991-TRFZNA, sy-vline,
  WA_A991-TRFZNZ, sy-vline,
  WA_A991-KFRST, sy-vline,
  WA_A991-DATBI, sy-vline,
  WA_A991-DATAB, sy-vline,
  WA_A991-KBSTAT, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_A991 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_A991 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_A991 INTO WA_A991.


*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 TDLNR
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_OUTPUT'
  EXPORTING
    input =                      WA_A991-TDLNR
  IMPORTING
    output =                     ld_input.
WRITE:/ 'Org Value:', WA_A991-TDLNR.
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_A991_STR, 
MANDT TYPE STRING,
KAPPL TYPE STRING,
KSCHL TYPE STRING,
TDLNR TYPE STRING,
LPRIO TYPE STRING,
TRFZNA TYPE STRING,
TRFZNZ TYPE STRING,
KFRST TYPE STRING,
DATBI TYPE STRING,
DATAB TYPE STRING,
KBSTAT TYPE STRING,
KNUMH TYPE STRING,END OF T_EKKO_STR.
DATA: WA_A991_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_A991_STR-MANDT sy-vline 
WA_A991_STR-KAPPL sy-vline 
WA_A991_STR-KSCHL sy-vline 
WA_A991_STR-TDLNR sy-vline 
WA_A991_STR-LPRIO sy-vline 
WA_A991_STR-TRFZNA sy-vline 
WA_A991_STR-TRFZNZ sy-vline 
WA_A991_STR-KFRST sy-vline 
WA_A991_STR-DATBI sy-vline 
WA_A991_STR-DATAB sy-vline 
WA_A991_STR-KBSTAT sy-vline 
WA_A991_STR-KNUMH sy-vline      INTO ld_text SEPARATED BY SPACE.

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