Need clarification on select query Urgent!!!!!

Question

Hi ,
i want clarification about this query , because i want improve performence to report in ST05 it is showing 1,40,250 time so i need to do some thing on this please any body help me out.
SELECT  matnr  werks  dispo
             FROM   marc
             INTO   TABLE  it_marc
                    WHERE  matnr  IN  s_matnr  AND
                           werks  IN  s_werks  AND
                           dispo  EQ  p_dispo.
    DESCRIBE TABLE it_marc  LINES w_lines.
    IF  w_lines  IS INITIAL.
      MESSAGE e518(zv) WITH p_dispo.
    ENDIF.
  ENDIF.
thanks,
murali.

Answer 1

SELECT matnr
  FROM mara
  INTO TABLE it_mara
  WHERE matnr IN s_matnr.
IF sy-subrc eq 0.
  SELECT matnr werks dispo
    FROM marc
    INTO TABLE it_marc
    FOR ALL ENTRIES IN it_mara
    WHERE matnr = it_mara-matnr
      AND werks IN s_werks
      AND dispo EQ p_dispo.
  DESCRIBE TABLE it_marc LINES w_lines.
  IF w_lines IS INITIAL.
    MESSAGE e518(zv) WITH p_dispo.
  ENDIF.
ENDIF.
I am sorry, but I comment also bad recommendations, if I find any. And the above example such
a bad recommendation.
SELECT matnr
  FROM mara
  INTO TABLE it_mara
  WHERE matnr IN s_matnr.
The first select selects much more than you really need, while there is only a select single necessary.
  DESCRIBE TABLE it_marc LINES w_lines.
  IF w_lines IS INITIAL.
It is also not necessary to count 1000 of lines, if you want to know whether there was at least one records, a check
of a sy-subrc is much better. This should also be done in the original coding.
As said above, check what is in s_matnr and s_werks and what is suppossed to come back.
Siegfried