> I've tried a lot of combinations but nothing worked.
>
> Can somebody send me an example?

I'm afraid that in unmanaged case you cannot do this. Specs say that
transaction is always associated with the connection object. So,
after you obtained a connection, you have a transaction, after you
commited(), you do have a transaction (another than before, but
anyway that's a transaction). Same with rollback()...

Hope this helps.
Roman