How to count the number of Rows to be Updated before Update takes place..

Question

Hi all,
I have a requirement, where i have to count the number of rows to be updated before updating it. SQL%ROWCOUNT gives the no. of rows updated ( after update takes place). How do i get to know the count of no. of rows to be updated/inserted/ deleted. I was looking for a simple solution, as above SQL%Rowcount. But i couldn't find any. I can use a Function and Return the value which will give me number of rows to be updated, But is there any Simple Logic other than this.. or any count function. Your Help is Appreciated. Thanks!

Answer 1

If you really want to do this (I have no clue why you would need it), then you can piggy back on any existing pessimistic locking you may already have in place.
However, it would require two loops through the records of which you want to know the count before you update, and a second pass to update them.
I would really re-think the need for this, though.
SQL> create table t0304(c number);
Table created.
SQL> insert into t0304 select rownum from all_objects where rownum <= 10;
10 rows created.
SQL> commit;
Commit complete.
SQL> select * from t0304;
         C
         1
         2
         3
         4
         5
         6
         7
         8
         9
        10
10 rows selected.
SQL> declare
  2    cursor mycursor is select * from t0304 where mod(c,2) = 0 for update;
  3    i number := 0;
  4  begin
  5    for r in mycursor loop
  6      i := i + 1;
  7    end loop;
  8    dbms_output.put_line(i);
  9    for r in mycursor loop
10      update t0304 set c = c + 20 where current of mycursor;
11    end loop;
12  end;
13  /
5
PL/SQL procedure successfully completed.
SQL> commit;
Commit complete.
SQL> select * from t0304;
         C
         1
        22
         3
        24
         5
        26
         7
        28
         9
        30
10 rows selected.
SQL>Edited by: Steve Howard on Mar 4, 2011 5:57 PM