Update Global Temp Table in Oracle 11g

Question

Hi Experts,
Scenario: I have stored  procedure A which calls procedure B. Procedure B uses Global temp Tables(With On Commit Preserve Rows)  to work with the data.
I am trying to update one of the GTT in Proc B but unable to do it .. via SQL or via PL/SQL Cursor/Collection. There is no syntax nor logical error and the PL/SQL proc completes execution successfully but the rows are not getting updated. My Db version is Oralce 11g 11203.
Update statement is something like this.
Update <GTT>
SET amount1 = amount1 *-1, amount2 = amount2 *-1
where field1 = <value>
and field2 in ( Select filed2 from <table1> );
Any idea why would this update not work? Has anyone faced this issue in Oracle 11g??
Appreciate your suggestions & thanks in Advance for your inputs.
Cheers,
MS

Answer 1

Update statement is something like this.
Update <GTT>
SET amount1 = amount1 *-1, amount2 = amount2 *-1
where field1 = <value>
and field2 in ( Select filed2 from <table1> );
Any idea why would this update not work?
You already told us that it DOES work - no errors or exceptions.
It is trivial to determine if that update will do anything - just turn it into a SELECT and see if any rows are ntselected:
v_cnt INTEGER;
SELECT COUNT(*) INTO v_cnt FROM  myGTT
WHERE field1 = <value>
AND field2 in (Select field2 from <tablee1>);
Then take a look at the 'count' that you get.