Re: will I need nested transactions ?

Andreas wrote:
> Hi,
>
> will I need "nested transactions" which - as I read - aren't
> implemented, yet ?
>
> I have some objects that rely on each other.
> Each has a status like proposal, working, canceled.
>
> table-A   <---   table-B   <---   table-C   <---   table-D
>
> Those are  (1, OO)  relationships,
> A status change above gets cascaded down but not upwards.
> If I try to cancel a table-A-record every "lower" record in B, C, D
> should be canceled, too, when the transaction is committed.
> Since it is possible, that I cancel e.g. a table B object only its
> children should get updated but not table-A.
>
> I thought somthing along this to cancel a type B object:
>
> BEGIN
>    BEGIN
>        BEGIN
>               UPDATE table-D
>         END
>         if no error UPDATE table-C
>    END
>    if no error UPDATE table-B
> END
>
> Does this make sense and will it provide the necesary protection ?

I don't think it needs to be that complicated. Just wrap the whole lot
in one transaction and it will either all work or all fail:

BEGIN
   UPDATE table_d ...
   UPDATE table_c ...
   UPDATE table_d ...
COMMIT;

--
   Richard Huxton
   Archonet Ltd