Problems using CONNECT BY

Question

Hi. I'm having problems using the CONNECT BY feature in oracle 9.
I need to check which codes are causing loop between parent and child. In 10G I could use CONNECT_BY_ISCYCLE, but it is not available in 9i; so what I did was the following (if there's a better solution please let me know).
parent_id | child_id
111 | 777
777 | 111
this should cause a loop and I should be able to tell the user that code 111 or 777 (either) is causing the problem.
procedure check_for_loops(op_class_code OUT MY_TABLE.PARENT_ID%type)
IS
class_parent_id2 MY_TABLE.PARENT_ID%type;
BEGIN
for c1 in ( SELECT distinct parent_id FROM MY_TABLE )
->loop
->->SELECT parent_id
->->INTO class_parent_id2
->->FROM MY_TABLE
->->WHERE parent_id = c1.parent_id
->->CONNECT BY PRIOR parent_id = child_id
->->start with parent_id = c1.parent_id;
->end loop;
->exception
->when NO_DATA_FOUND then
->return;
->when others then
->if SQLCODE = -1436 THEN
->->for c2 in ( select distinct parent_id from MY_TABLE
->->where parent_id = c1.parent_id )
->->loop
->->->->op_class_code := c2.parent_id;
->->end loop;
->->else
->->->->raise;
->->end if;
end check_for_loops;
If there's a loop (the exception code is -1436), then I get the code and return it to the client.
However, in some situations the exception thrown is the following:
java.sql.SQLException: ORA-01422: exact fetch returns more than requested number of rows
is the connect by used correctly? Is there any other better way to retrieve the offending code that is causing the circular loop?
thanks

Answer 1

The code is working ok at the moment. I have a similar problem. I have two tables:
- stage_table (parent_id, child_id)
- active_table (parent_id, child_id)
(they both have the same structure)
stage_table is populated with data that will eventually be stored in active_table, once the validations are succesful.
What I'm trying to do is loop thru the stage table,and for every row I want to call the function to see if that row causes loop. my function is:
->FUNCTION check_for_loops_stage_table()
->RETURN EMPARRAY
->AS
->->l_codes EmpArray := EmpArray();
->->CURSOR c1 IS
->->->->select distinct parent_id
->->->->from stage_table
->->->->where my_iscycle( parent_id ) = 1;
->->BEGIN
->->->for rec in c1 LOOP
->->->->l_codes.extend;
->->->->l_codes(l_codes.last) := rec.parent_id;
->->->end loop;
->->RETURN l_codes;
->END check_for_loops_stage_table;
the cursor c1 is basically
(am I using EMPARRAY correctly?). As you can see, I want to put all the codes that are failing into an EMPARRAY, so I can later on retrieve that emparray from java and deal with it.
the my_iscycle function is:
FUNCTION my_iscycle(p_parent_id IN stage_table.parent_id%type)
RETURN stage_table.parent_ID%type
AS
-> v_count NUMBER;
->BEGIN
->->SELECT COUNT (*)
->->INTO v_count
->->FROM (SELECT parent_id
->->->->FROM active_table
->->->->START WITH parent_id = p_parent_id
->->->->CONNECT BY PRIOR parent_id = child_id);
->->->RETURN 0;
->->EXCEPTION
->->->->WHEN OTHERS THEN
->->->->IF SQLCODE = -1436 THEN
->->->->->RETURN 1;
->->->->END IF;
->END my_iscycle
If I have in my active_table
parent_id | child_id
111 | 777
and then in my stage_table I have
parent_id | child_id
777 | 111
the result I get from EMPARRAY is empty. So it doesn't seem to find the loop, don't know why. Any ideas?