怎样在Oracle 10g存储过程中log错误行

CREATE OR REPLACE PROCEDURE top_logging IS
  demo number;
begin
  select * into demo from dual;
EXCEPTION
  WHEN OTHERS THEN
    dbms_output.put_line(dbms_utility.format_error_backtrace());
END top_logging;
/
 
SQL> exec TOP_LOGGING;
ORA-06512: 在 "SYS.TOP_LOGGING", line 4