我有与ddl触发器相关的问题：

create or replace trigger audit_ddl_db_trg after ddl on database
begin
DECLARE
    n number;
    stmt     varchar2(4000);
    sql_text ora_name_list_t;
  begin
      dbms_output.put_line(ora_sql_txt(sql_text));
          n := ora_sql_txt(sql_text);
          IF nvl(n,200)=200 THEN
                           Raise_application_error(-20001, 'ora_sql_txt does not catch any statement. sql_txt is not initialized');
          ELSE FOR i IN 1..n LOOP
                    stmt := stmt || sql_text(i);
            END LOOP;
            dbms_output.put_line(stmt);
          END IF;

    IF ora_sysevent <> 'TRUNCATE'
    THEN
  if (ora_sysevent='TRUNCATE')
  then
    null; -- I do not care about truncate
  else
    insert into audit_ddl(date_of_change,osuser,current_user,host,terminal,owner,object_type,object_name,ora_sysevent,sqltext)
    values(
      systimestamp,
      sys_context('USERENV','OS_USER') ,
      sys_context('USERENV','CURRENT_USER') ,
      sys_context('USERENV','HOST') ,
      sys_context('USERENV','TERMINAL') ,
      ora_dict_obj_owner,
      ora_dict_obj_type,
      ora_dict_obj_name,
      ora_sysevent,
      stmt
    );
    end if;
    end if;
    end;
end;

触发器可以正确捕获所有内容，我的表中确实填充了所有内容，但是我确实有与列current_user相关的问题。无论我在数据库中使用哪种用户架构进行更改，它都会写入SYS。如何用做过修改的正确用户来填充呢？

谢谢！