Error On Oracle Function That Recursively Selects child elements of parent - sql

Question

I am trying to write an oracle function that takes in a parentID and returns me a "table" that recursively finds its child and child's child and so on.. Here is my code for it but whenever I try and create the function I get these errors :
[Error] Compilation (17: 10): ORA-00604 : error occurred at recursive SQL level 1
ORA-01422 : exact fetch returns more than requested number of rows
ORA-06512
ORA-06512
And here is code:
CREATE OR REPLACE TYPE TAB_TableOfIDs IS TABLE OF NUMBER;
CREATE OR REPLACE FUNCTION RETURNCHILDIDS (pParentID NUMBER)
RETURN TAB_TableOfIDs
AS
ResultSet TAB_TableOfIDs;
BEGIN
WITH MY_VIEW (ID)
AS (SELECT A.ID
FROM MYTABLE A
WHERE A.ID = pParentID
UNION ALL
SELECT E.ID
FROM MYTABLE E
INNER JOIN MY_VIEW B
ON E.ParentID = B.ID)
select bulk collect into ResultSet from MY_VIEW;
RETURN ResultSet;
END;
/
The interesting part is , the code just works fine in a normal SQL query editor but if you put it in a function it gives the error.. So what am I doing wrong? and how can I fix it?
Thank you in advance.

Answer 1

I had my solution :
CREATE OR REPLACE FUNCTION RETURNCHILDIDS (pParentID NUMBER)
RETURN TAB_TableOfIDs
IS
CURSOR c1
IS
WITH ALT_BIRIM (targetID, ID, parentID)
AS (SELECT A.targetID, A.ID, A.PARENTID
FROM ENTKURUM A
WHERE A.ID = (SELECT ID
FROM ENTKURUM
WHERE targetID = pParentID)
UNION ALL
SELECT E.targetID, E.ID, E.PARENTID
FROM ENTKURUM E
INNER JOIN ALT_BIRIM B
ON E.PARENTID = B.ID)
SELECT targetID
FROM alt_birim;
ResultSet TAB_TableOfIDs := NEW TAB_TableOfIDs ();
BEGIN
FOR mrow IN c1
LOOP
ResultSet.EXTEND ();
ResultSet (ResultSet.COUNT) := mrow.targetID;
END LOOP;
RETURN ResultSet;
END;

Answer 2

Either:
Rewrite your SELECT INTO statement so that only one row is returned.
OR
Create a cursor and retrieve each row if you are unsure of how many records you might retrieve.
CREATE OR REPLACE FUNCTION RETURNCHILDIDS (pParentID IN NUMBER)
RETURN number
IS
cnumber number;
CURSOR c1
IS
[Your query]
...
BEGIN
OPEN c1;
FETCH c1 INTO cnumber;
CLOSE c1;
RETURN cnumber;
END;