Connected.
SANDBOX@ee>;create table my_table (my_column number);

Table created.
SANDBOX@ee>;
SANDBOX@ee>;create table my_log(time timestamp with local time zone, message varchar2(2000));

Table created.
SANDBOX@ee>;create or replace trigger my_trigger
  2  before insert or update or delete
  3  on my_table
  4  declare
  5      pragma autonomous_transaction;
  6      message my_log.message%type;
  7  begin
  8      case
  9          when inserting then
 10              message := 'INSERTING';
 11          when updating then
 12              message := 'UPDATING';
 13          when deleting then
 14              message := 'DELETING';
 15          else
 16              null;
 17      end case;
 18      insert into my_log(time, message)
 19          values (current_timestamp, message);
 20      commit;
 21  end;
 22  /

Trigger created.
SANDBOX@ee>;insert into my_table(my_column) values(1);

1 row created.
SANDBOX@ee>;select * from my_log;
TIME                          MESSAGE
----------------------------- ----------
25-NOV-16 04.23.49.239000 PM  INSERTING

SANDBOX@ee>;update my_table set my_column = 2;

1 row updated.
SANDBOX@ee>;select * from my_log;
TIME                          MESSAGE
----------------------------- ----------
25-NOV-16 04.23.49.239000 PM  INSERTING
25-NOV-16 04.23.49.310000 PM  UPDATING

SANDBOX@ee>;delete from my_table;

1 row deleted.
SANDBOX@ee>;select * from my_log;
TIME                          MESSAGE
----------------------------- ----------
25-NOV-16 04.23.49.239000 PM  INSERTING
25-NOV-16 04.23.49.310000 PM  UPDATING
25-NOV-16 04.23.49.363000 PM  DELETING

SANDBOX@ee>;rollback;

Rollback complete.
SANDBOX@ee>;select * from my_log;
TIME                          MESSAGE
----------------------------- ----------
25-NOV-16 04.23.49.239000 PM  INSERTING
25-NOV-16 04.23.49.310000 PM  UPDATING
25-NOV-16 04.23.49.363000 PM  DELETING