Recursive sum of values in an hierarchical table in Oracle 10g - view

Question

Assuming I have this table:
CREATE TABLE MY_EXAMPLE ( ID NUMBER , PARENT NUMBER , VALUE NUMBER );
Insert into MY_EXAMPLE (ID,PARENT,VALUE) values (1,null,100);
Insert into MY_EXAMPLE (ID,PARENT,VALUE) values (2,1,50);
Insert into MY_EXAMPLE (ID,PARENT,VALUE) values (3,null,0);
Insert into MY_EXAMPLE (ID,PARENT,VALUE) values (4,2,1000);
Insert into MY_EXAMPLE (ID,PARENT,VALUE) values (5,1,1);
|id |parent |value |
|1 |null |100 |
|2 |1 |50 |
|3 |null |0 |
|4 |2 |1000 |
|5 |1 |1 |
I need to create a view (which should perform well) with the same number of rows but giving the row's plus the children's value summed. Many levels are possible as well as many children.
|id |parent |value |
|1 |null |1151 | (sum of 1 + 2 + 4 + 5)
|2 |1 |1050 | (sum of 2 + 4)
|3 |null |0 | (only 3 because has no children)
|4 |2 |1000 | (only 4 because has no children)
|5 |1 |1 | (only 5 because has no children)
ps.: I tried something like this but it didn't work in Oracle 10g first because the keyword RECURSIVE is not supported and second because it won't allow recursive WITH ("forward or recursive reference of a query name in WITH clause is not allowed").
Also I couldn't figure out a way to do it with CONNECT BY that includes the id and parent columns and gives me the whole table (in my attempts I always had to use START WITH).

Answer 1

You will have to create a recursive function:
CREATE FUNCTION RECURSIVE_ADD(
ROOT_ID IN NUMBER)
RETURN NUMBER
IS
TOTAL NUMBER;
BEGIN
SELECT SUM(VALUE)
INTO TOTAL
FROM (
(
SELECT VALUE FROM MY_EXAMPLE WHERE ID = ROOT_ID
)
UNION
(
SELECT recursive_add(id) FROM my_example WHERE parent = root_id
));
RETURN total;
END;
select id, parent, value, RECURSIVE_ADD(id) from my_example;
Make sure you don't have a cycle in your data (for example, if you set the parent of 1 to 2) otherwise this will never terminate. There are other ways to do this in newer versions of Oracle, but this will work in 10g.