Oracle 如何使用spool命令将sql脚本resultset保存到文件中，并且文件名包括 “日期格式”？

SET heading       ON
SET echo            OFF
SET feedback     OFF
SET trimspool     ON
SET newpage     NONE
SET verify           OFF
SET define          OFF
SET termout        OFF
SET timing          OFF
 
SET linesize    400
SET pagesize  0
 
SPOOL check_redo_apply_xxxxxxxxxxxxxx.log
 
COL current_scn FOR 9999999999999999
 
SELECT current_scn FROM v$database;
 
SELECT MAX(sequence#) FROM v$archived_log WHERE applied='YES';
 
SELECT MAX(sequence#) FROM v$archived_log WHERE applied='NO';
 
SELECT process,pid,status,sequence#,block#,blocks,delay_mins FROM v$managed_standby;
 
SELECT sequence#,status,archived FROM v$standby_log;
 
COL name                   FOR  a24
COL value                   FOR  a12
COL unit                      FOR  a28
COL time_computed   FOR  a20
COL datum_time         FOR  a20
 
SELECT * FROM v$dataguard_stats;
 
SPOOL OFF

SQL> column dt new_value filedt
SQL> select to_char(sysdate,'YYYYMMDD') dt from dual;

DT
--------
20170710

SQL> spool &filedt..log
SQL> spool off
SQL> ho dir *.log
 Volume in drive C is System
 Volume Serial Number is E6AB-58D8

 Directory of C:\temp

10/07/2017  10:45                16 20170710.log
               1 File(s)             16 bytes
               0 Dir(s)  149,895,012,352 bytes free