ABAP Select data from SAP table CACHE_BUF_CHAINS into internal table

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

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

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

*Select data and declare internal table using in-line method @DATA
*SELECT *
*  FROM CACHE_BUF_CHAINS
*  INTO TABLE @DATA(IT_CACHE_BUF_CHAINS2).
*--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_CACHE_BUF_CHAINS INDEX 1 INTO DATA(WA_CACHE_BUF_CHAINS2).


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

*To update a field value using a field symbol simply change the value via the field symbol pointer
<CACHE_BUF_CHAINS>-INST_ID = 1.
<CACHE_BUF_CHAINS>-CHILD = 1.
<CACHE_BUF_CHAINS>-ADDR = 1.
<CACHE_BUF_CHAINS>-WAIT_TIME = 1.
<CACHE_BUF_CHAINS>-PTIME = 1.

ENDLOOP.

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

*Write selected data to screen/report before conversion.
  WRITE:/ sy-vline,   WA_CACHE_BUF_CHAINS-PTOTTIME, sy-vline,
  WA_CACHE_BUF_CHAINS-GETS, sy-vline,
  WA_CACHE_BUF_CHAINS-PGETS, sy-vline,
  WA_CACHE_BUF_CHAINS-MISSES, sy-vline,
  WA_CACHE_BUF_CHAINS-PMISSES1, sy-vline,
  WA_CACHE_BUF_CHAINS-SLEEPS, sy-vline.
ENDLOOP.
   
*Add any further fields from structure WA_CACHE_BUF_CHAINS 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_CACHE_BUF_CHAINS 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_CACHE_BUF_CHAINS INTO WA_CACHE_BUF_CHAINS.


*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_CACHE_BUF_CHAINS_STR, 
INST_ID TYPE STRING,
CHILD TYPE STRING,
ADDR TYPE STRING,
WAIT_TIME TYPE STRING,
PTIME TYPE STRING,
PTOTTIME TYPE STRING,
GETS TYPE STRING,
PGETS TYPE STRING,
MISSES TYPE STRING,
PMISSES1 TYPE STRING,
SLEEPS TYPE STRING,
PSLEEPS1 TYPE STRING,
PTOTSLEEPS TYPE STRING,
IMM_GETS TYPE STRING,
IMM_MISSES TYPE STRING,
PMISSES2 TYPE STRING,
WAITHLDLTC TYPE STRING,
SPIN_GETS TYPE STRING,
PSLEEPS2 TYPE STRING,END OF T_EKKO_STR.
DATA: WA_CACHE_BUF_CHAINS_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_CACHE_BUF_CHAINS_STR-INST_ID sy-vline 
WA_CACHE_BUF_CHAINS_STR-CHILD sy-vline 
WA_CACHE_BUF_CHAINS_STR-ADDR sy-vline 
WA_CACHE_BUF_CHAINS_STR-WAIT_TIME sy-vline 
WA_CACHE_BUF_CHAINS_STR-PTIME sy-vline 
WA_CACHE_BUF_CHAINS_STR-PTOTTIME sy-vline 
WA_CACHE_BUF_CHAINS_STR-GETS sy-vline 
WA_CACHE_BUF_CHAINS_STR-PGETS sy-vline 
WA_CACHE_BUF_CHAINS_STR-MISSES sy-vline 
WA_CACHE_BUF_CHAINS_STR-PMISSES1 sy-vline 
WA_CACHE_BUF_CHAINS_STR-SLEEPS sy-vline 
WA_CACHE_BUF_CHAINS_STR-PSLEEPS1 sy-vline 
WA_CACHE_BUF_CHAINS_STR-PTOTSLEEPS sy-vline 
WA_CACHE_BUF_CHAINS_STR-IMM_GETS sy-vline 
WA_CACHE_BUF_CHAINS_STR-IMM_MISSES sy-vline 
WA_CACHE_BUF_CHAINS_STR-PMISSES2 sy-vline 
WA_CACHE_BUF_CHAINS_STR-WAITHLDLTC sy-vline 
WA_CACHE_BUF_CHAINS_STR-SPIN_GETS sy-vline 
WA_CACHE_BUF_CHAINS_STR-PSLEEPS2 sy-vline      INTO ld_text SEPARATED BY SPACE.

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