BEGIN
  DBMS_FGA.ADD_POLICY(
   object_schema      => 'SCOTT',
   object_name        => 'TB_LOG',
   policy_name        => 'CHK_HR_TB_LOG',
   enable             =>  TRUE,
   statement_types    => 'INSERT, UPDATE, SELECT, DELETE',
   audit_trail        =>  DBMS_FGA.DB);
END;

select count(1) from tb_log;
delete from tb_log;

SQL> select  sessionid, oshst, sqltext from FGA_LOG$;

 SESSIONID OSHST                SQLTEXT
---------- -------------------- --------------------
       228 WORKGROUP\HXL
       228 WORKGROUP\HXL