ABAP Select data from SAP table MERGEH into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM MERGEH
*  INTO TABLE @DATA(IT_MERGEH2).
*--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_MERGEH INDEX 1 INTO DATA(WA_MERGEH2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<MERGEH>-ID = 1.
<MERGEH>-MAPNAME = 1.
<MERGEH>-STEP = 1.
<MERGEH>-POS = 1.
<MERGEH>-SAPRELEASE = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_MERGEH-SOURCEREL, sy-vline,
  WA_MERGEH-TRKORR, sy-vline,
  WA_MERGEH-MERGEDATE, sy-vline,
  WA_MERGEH-MERGETIME, sy-vline,
  WA_MERGEH-STARTDATE, sy-vline,
  WA_MERGEH-STARTTIME, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_MERGEH 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_MERGEH 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_MERGEH INTO WA_MERGEH.


*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_MERGEH_STR, 
ID TYPE STRING,
MAPNAME TYPE STRING,
STEP TYPE STRING,
POS TYPE STRING,
SAPRELEASE TYPE STRING,
SOURCEREL TYPE STRING,
TRKORR TYPE STRING,
MERGEDATE TYPE STRING,
MERGETIME TYPE STRING,
STARTDATE TYPE STRING,
STARTTIME TYPE STRING,
ENDDATE TYPE STRING,
ENDTIME TYPE STRING,
MAX_TA TYPE STRING,
HANDLED_TA TYPE STRING,
STATUS TYPE STRING,END OF T_EKKO_STR.
DATA: WA_MERGEH_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_MERGEH_STR-ID sy-vline 
WA_MERGEH_STR-MAPNAME sy-vline 
WA_MERGEH_STR-STEP sy-vline 
WA_MERGEH_STR-POS sy-vline 
WA_MERGEH_STR-SAPRELEASE sy-vline 
WA_MERGEH_STR-SOURCEREL sy-vline 
WA_MERGEH_STR-TRKORR sy-vline 
WA_MERGEH_STR-MERGEDATE sy-vline 
WA_MERGEH_STR-MERGETIME sy-vline 
WA_MERGEH_STR-STARTDATE sy-vline 
WA_MERGEH_STR-STARTTIME sy-vline 
WA_MERGEH_STR-ENDDATE sy-vline 
WA_MERGEH_STR-ENDTIME sy-vline 
WA_MERGEH_STR-MAX_TA sy-vline 
WA_MERGEH_STR-HANDLED_TA sy-vline 
WA_MERGEH_STR-STATUS sy-vline      INTO ld_text SEPARATED BY SPACE.

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