nls_date_format参数设置的问题


SQL> select sysdate from dual;SYSDATE
---------------
19-OCT-09
SQL> alter session set nls_date_format="MON-DD-YYYY";Session altered.
SQL> select sysdate from dual;SYSDATE
-----------------
OCT-19-2009SQL>可是好像我用ALTER SYSTEM设置nls_date_format则达不到效果SQL> alter system set nls_date_format="MON-DD-YYYY" scope=spfile;System altered.SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.Total System Global Area  176160768 bytes
Fixed Size                  1247948 bytes
Variable Size              92276020 bytes
Database Buffers           79691776 bytes
Redo Buffers                2945024 bytes
Database mounted.
Database opened.
SQL> show parameter date
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
fixed_date                           string
nls_date_format                      string      MON-DD-YYYY
nls_date_language                    stringSQL> select sysdate from dual;SYSDATE
---------------
19-OCT-09SQL>这个时候为什么不显示OCT-19-2009 而却是19-OCT-09