Using “nested” transactions in oracle

Question

I have troubles with transactions in Oracle. I have some procedures like this:

create or replace procedure myschema.DataSave(v_value IN NUMBER)
as
begin

SET         


        

Answer 1

Exceptions are restricted to the program group they are raised in.

create or replace procedure myschema.DataSave(v_value IN NUMBER)
as

ex_dml_error EXCEPTION;
begin


begin
insert/update/delete...
exception 
    when OTHERS then ex_dml_error;
end;

COMMIT;

EXCEPTION 
   WHEN ex_dml_error THEN
     ROLLBACK;
end;
/

Answer 2

Oracle doesn't support nested transactions. If a transaction commits, it commits. That's why you generally don't want to commit (or rollback) a transaction in a stored procedure, that makes it difficult to reuse the procedure elsewhere if your transaction semantics differ.

You can, however, declare a savepoint at the beginning of your procedure and rollback to that savepoint in the case of an error. If you then remove the commit, then the transaction is solely controlled by the application code not by the database code

begin
  savepoint beginning_of_proc;

  insert/update/delete...

exception 
  when OTHERS then 
    rollback to beginning_of_proc;
    raise;
end;

In this case, though, my bias would be not to have a savepoint in the code, not to have a rollback, and not to catch the exception unless you're doing something useful with it. Just do the DML, let any exceptions get thrown, and handle them in your application.