Optimize SELECT statement

Question

Hello Colleagues,
Please assist me in optimizing the two SELECT statement which is taking too much time
1. SELECT SINGLE COUNT(*) FROM j_3abdsi
                          WHERE matnr IN r_matnr
                            AND j_4krcat EQ im_valcat.
-- I just need to check whether there are entries in the table with this criteria. 
2.   SELECT e~vbeln FROM ( vbep AS e
         INNER JOIN vbap AS p ON pvbeln = evbeln
                        AND pposnr = eposnr )
          INTO lv_vbeln
         WHERE p~matnr IN r_matnr
           AND e~j_4krcat eq im_valcat.
    EXIT.
  ENDSELECT.
-- here also the case is same. Just need to check whether any value exist.
Kindly help.
Regards
Sudha
Edited by: Sudha Naik on Oct 8, 2009 7:32 AM

Answer 1

Hi Sudha,
1) I do not understand why you would say SELECT SINGLE COUNT(). If you know the entire primary key and would like to retrieve a record you will use SELECT SINGLE to retrieve just that single record. SELECT COUNT() returns the number of records meeting your selection criteria in the system field SY-DBCNT. SELECT COUNT(*) is generally used to check for the existance of the record because this construct just check the number of qualifying records and does not retrieve any data fields from the table. You seem to have merged both these statements and have created something I have never seen before. If you are only interested in finding the existance of the record may I suggest that you use the following.
DATA: w_matnr TYPE mara-matnr.
SELECT matnr
  UP TO 1 ROWS
  FROM j_3abdsi
  WHERE matnr    IN r_matnr
  AND   j_4krcat EQ im_valcat.
ENDSELECT.
SELECT COUNT(*) is good if you are using an index. If not you will be trying to count the records without an index. This can be time consuming. If you are not interested in the record count and only want to know if a qualifying record exist the above option will be faster because SAP check for the first instance and then returns SY-SUBRC = 0.
2) Use the following code.
SELECT e~vbeln
  UP TO 1 ROWS
  FROM       vbap AS p
  INNER JOIN vbep AS e
  ON  p~vbeln = e~vbeln
  AND p~posnr = e~posnr )
  INTO lv_vbeln
  WHERE p~matnr    IN r_matnr
  AND   e~j_4krcat EQ im_valcat.
ENDSELECT.