Give me best one

Question

Hi Friends,
I have following query . Can you pls give best one in performance point of view and tell me why also..
*To fetch Material to BoM link related data
SELECT matnr stlnr FROM mast
       INTO TABLE it_mast
       FOR ALL ENTRIES IN it_fp
       WHERE matnr EQ it_fp-matnr AND stlal EQ c_stlal_01.
*To fetch Base Quantity of BOM from STKO
LOOP AT it_mast.
  SELECT SINGLE bmeng INTO it_mast-bmeng
       FROM stko
       WHERE stlnr EQ it_mast-stlnr.
  MODIFY it_mast.
ENDLOOP.
Thanks IN Advance,
Murali Krishna K

Answer 1

Murali,
Let us start with analysing your code.
<b>You have not mentioned the structure of internal table it_fp. Is MATNR a unique field in this table? If so ok, otherwise you will be looping at the database multiple times for the same material number. You must ensure that the selection criteria being used in a for all entries clause is unique. Secondly it is very important that you check for the emptiness of internal table it_fp before this select using the for all entries clause. If you don't and it_fp happened to be empty SAP will download all the records from database table MAST into your internal table. This will cause a performance issue and may cause a dump if the quantity of data being retrieved is larger than the default maximum size of the internal table set during installation of SAP by the BASIS people. Thirdly when you use a for all entries clause you should include all the primary key fields of table MAST in the field list of the select to avoid data loss.</b>
SELECT matnr stlnr FROM mast
INTO TABLE it_mast
FOR ALL ENTRIES IN it_fp
WHERE matnr EQ it_fp-matnr AND stlal EQ c_stlal_01.
*To fetch Base Quantity of BOM from STKO
LOOP AT it_mast.
<b>Use a select within a loop only if it is a select single on a fully buffered table. For all other cases do not use a select within a loop. Secondly do not use a select single unless your where clause has all the primary key fields, meaning do not use select single unless you are sure that you will get a single unique record. In your case STLNR is not the only primary key field. You should have used select up to 1 rows, however not within a loop. Thirdly always use the transporting clause while modifying an internal table within a loop. If not you will be modifying all the fields of the current record of the internal table with the data in the header of the internal table. This is an overhead. If you are changing just one value there is no need to modify all the fields of the internal table. The Transporting clause is used for precisely that reason. </b>
SELECT SINGLE bmeng INTO it_mast-bmeng
FROM stko
WHERE stlnr EQ it_mast-stlnr.
MODIFY it_mast.
ENDLOOP.
<b>If I were to write this same piece of code I would do so as follows. Please note that you will have to check and correct this code for syntax errors.</b>
DATA: it_fp_tmp   LIKE TABLE OF it_fp  ,
      it_mast_tmp LIKE TABLE OF it_mast.
IF NOT it_fp[] IS INITIAL.
  it_fp_tmp[] = it_fp[].
  SORT it_fp_tmp BY matnr.
  DELETE ADJACENT DUPLICATES FROM it_fp_tmp COMPARING matnr.
  SELECT stlnr
         matnr
         werks
         stlan
         stlnr
         stlal
   FROM mast
   INTO TABLE it_mast
   FOR ALL ENTRIES IN it_fp_tmp
   WHERE matnr EQ it_fp_tmp-matnr
   AND   stlal EQ c_stlal_01.
  IF sy-subrc EQ 0.
    SORT it_mast BY stlnr.
    it_mast_tmp[] = it_mast[].
    DELETE ADJACENT DUPLICATES FROM it_mast_tmp COMPARING stlnr.
    SELECT stlty
           stlnr
           stlal
           stkoz
           bmeng
      FROM stko
      INTO TABLE it_stko
      FOR ALL ENTRIES IN it_mast_tmp
      WHERE stlnr EQ it_mast_tmp-stlnr.
    IF sy-subrc EQ 0.
      SORT it_mast_tmp BY stlnr.
    ENDIF.
  ENDIF.
ENDIF.
*To fetch Base Quantity of BOM from STKO
LOOP AT it_mast.
  AT NEW stlnr.
    READ TABLE it_stko WITH KEY stlnr = it_mast-stlnr
                                BINARY SEARCH
                                TRANSPORTING
                                  bmeng.
  ENDAT.
  IF NOT it_stko-bmeng IS INITIAL.
    it_mast-bmeng = it_stko-bmeng.
    MODIFY it_mast TRANSPORTING
                     bmeng.
  ENDIF.
ENDLOOP.