FOR Loop Exception Handling

Question

Given the following code:
for x in my_cursor loop
    begin
        <<stmt_1>>
        <<stmt_2>>
    exception
        when others then
            <<log_error>>
    end;
end loop;Say there are 5 x's in my_cursor. On element x3, stmt_1 works fine but stmt_2 throws an exception. I'd like to rollback ONLY the work done on x3 (in this case, stmt_1), then continue the loop from the next element, x4. Can this be achieved with some combination of savepoint/rollback?

Answer 1

As I said, you can put the increment operation at the end of the block when you know no more exceptions could be raised, i.e.
declare
    cnt number;
    ex  exception;
begin
    cnt := 0;
    for x in 1..5 loop
        begin
            savepoint s;
            insert into test_tbl values(1/(3-x));
            cnt := cnt+1;
        exception
            when others then
                rollback to savepoint s;
        end;
    end loop;
    dbms_output.put_line('cnt='||cnt);
end;You could also increment the counter outside of the PL/SQL block, i.e.
declare
    cnt number;
    ex  exception;
    num_success number;
begin
    cnt := 0;
    for x in 1..5 loop
        begin
            num_success := 0;
            savepoint s;
            insert into test_tbl values(1/(3-x));
            num_success := sql%rowcount;
        exception
            when others then
                rollback to savepoint s;
        end;
        cnt := cnt + num_success;
    end loop;
    dbms_output.put_line('cnt='||cnt);
end;And you can refactor your code so that the components to hide some of this complexity, i.e.
SQL> ed
Wrote file afiedt.buf
  1  create or replace procedure try_insert_test_tbl(
  2    p_val in number,
  3    p_num_success out number )
  4  as
  5    divide_by_zero exception;
  6    pragma exception_init( divide_by_zero, -1476 );
  7  begin
  8    savepoint s;
  9    insert into test_tbl values( 1/(3-p_val ) );
10    p_num_success := sql%rowcount;
11  exception
12    when divide_by_zero
13    then
14      p_num_success := 0;
15* end;
SQL> /
Procedure created.
SQL> ed
Wrote file afiedt.buf
  1  declare
  2      cnt number;
  3      ex  exception;
  4      num_success number;
  5  begin
  6      cnt := 0;
  7      for x in 1..5 loop
  8          try_insert_test_tbl( x, num_success );
  9          cnt := cnt + num_success;
10      end loop;
11      dbms_output.put_line('cnt='||cnt);
12* end;
SQL> /
cnt=4
PL/SQL procedure successfully completed.There is no way for DCL statements to affect the state of PL/SQL variables. But you can generally structure your code in such a way that this is unnecessary.
Justin