oracle 重置初始化参数 reset parameter value

先前更改了os_authent_prefix为空，后来想改回原来的值，如果你不知道原值怎么办？重置
connect !
SQL> show parameter os

NAME TYPE
------------------------------------ ----------------------
VALUE
------------------------------
optimizer_index_cost_adj integer
100
os_authent_prefix string
SQL> alter system reset os_authent_prefix scope=spfile ;
alter system reset os_authent_prefix scope=spfile
*
ERROR at line 1:
ORA-00905: missing keyword
SQL> alter system reset os_authent_prefix scope=spfile sid=*;
alter system reset os_authent_prefix scope=spfile sid=*
*
ERROR at line 1:
ORA-01780: string literal required
SQL> alter system reset os_authent_prefix scope=spfile sid='*';

System altered.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 562036736 bytes
Fixed Size 1220556 bytes
Variable Size 239075380 bytes
Database Buffers 314572800 bytes
Redo Buffers 7168000 bytes
Database mounted.
Database opened.
SQL> set linesize 200
SQL> show parameter os_au

NAME TYPE VALUE
------------------------------------ ---------------------- ------------------------------
os_authent_prefix string ops$
remote_os_authent boolean FALSE
SQL>
到此修改完成，至于为什么非要加sid, 记的在TOM大叔的书上有讲，是出于考虑多实例。