oracle修改字符集（WE8MSWIN1252 -->ZHS16GBK）

查看数据库当前字符集

SQL> select userenv('language') from dual;

USERENV('LANGUAGE')
----------------------------------------------------
AMERICAN_AMERICA.WE8MSWIN1252
--------------------- 

将数据库置于restricted mode下

SQL> alter system enable restricted session;
System altered.

修改字符集到ZHS16GBK

SQL> ALTER DATABASE CHARACTER SET ZHS16GBK; 
ALTER DATABASE CHARACTER SET ZHS16GBK 
*  
ERROR at line 1: 
ORA-12712: new character set must be a superset of old character set 

提示我们的字符集：新字符集必须为旧字符集的超集，这时我们可以跳过超集的检查做更改：

SQL> ALTER DATABASE character set INTERNAL_USE ZHS16GBK; 
ALTER DATABASE character set INTERNAL_USE ZHS16GBK
*
ERROR at line 1:
ORA-12721: operation cannot execute when other sessions are active

当前有连接处于active状态，kill掉session或者重启数据库。

SQL> shutdown immediate;
SQL> startup mount;

SQL> alter system enable restricted session;
System altered.

SQL> alter database open;
Database altered.

SQL> ALTER DATABASE character set INTERNAL_USE ZHS16GBK; 
Database altered.

SQL> alter system disable restricted session;
System altered.

SQL> select userenv('language') from dual;
USERENV('LANGUAGE')
----------------------------------------------------
AMERICAN_AMERICA.ZHS16GBK
----------------------------------------------------