Oracle修改已经创建的数据库字符集

我是从ZHS16GBK修改为US7ASCII

>sqlplus /nolog
SQL> conn /as sysdba;
Connected.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 1071333376 bytes
Fixed Size                  1375792 bytes
Variable Size             612368848 bytes
Database Buffers          452984832 bytes
Redo Buffers                4603904 bytes
Database mounted.
SQL> alter system enable restricted session;
System altered.
SQL> alter system set job_queue_processes=0;
System altered.
SQL> alter system set aq_tm_processes=0;
System altered.
SQL> alter database open;
Database altered.
SQL> alter database character set us7ascii;
alter database character set us7ascii
*
ERROR at line 1:
ORA-12712: new character set must be a superset of old character set

出现如上错误，要添加“internal_use”

SQL> alter database character set internal_use us7ascii;
Database altered.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup;
ORACLE instance started.
Total System Global Area 1071333376 bytes
Fixed Size                  1375792 bytes
Variable Size             612368848 bytes
Database Buffers          452984832 bytes
Redo Buffers                4603904 bytes
Database mounted.
Database opened.
SQL>

参考文章：

http://www.cnblogs.com/kerrycode/p/3749085.html

http://blog.csdn.net/nsj820/article/details/6571105