Question

i have in a procedure which fills a table the following sql

SELECT NVL(SUM(COL1), 0),
       NVL(SUM(COL2), 0)
  INTO v_mytable.COLUMN1,
       v_mytable.COLUMN2
  FROM t1, t2
 WHERE t1.id = t2.id
   AND t1.date = t2.date

also, for 99% of the table rows, those columns = 0 and this query take a long time to be executed when it will return 0 for both columns in most cases.

Is it better to use exception handeling as the following :

BEGIN
  SELECT SUM(COL1),
         SUM(COL2)
    INTO v_mytable.COLUMN1,
         v_mytable.COLUMN2
    FROM t1, t2
   WHERE t1.id = t2.id
     AND t1.date = t2.date
EXCEPTION WHEN NO_DATA_FOUND THEN
  v_mytable.COLUMN1 := 0 ;
  v_mytable.COLUMN2 := 0 ;
END;

Thanks.

Answer 1

Those two blocks do completely different things. Your SELECT statement would not throw a NO_DATA_FOUND error if COL1 and/or COL2 were always NULL. It would simply put a NULL in v_mytable.COLUMN1 and v_mytable.COLUMN2.

You could do

SELECT SUM(COL1),
       SUM(COL2)
  INTO v_mytable.COLUMN1,
       v_mytable.COLUMN2
  FROM t1, t2
 WHERE t1.id = t2.id
   AND t1.date = t2.date

v_mytable.COLUMN1 := NVL( v_mytable.COLUMN1, 0 );
v_mytable.COLUMN2 := NVL( v_mytable.COLUMN2, 0 );

I wouldn’t expect that to be any faster, however.