1.（Window：）cmd下输入set ORACLE_SID=你想进入的数据库的那个sid

（Linux：）切换到oracle用户：export ORACLE_SID=你想进入的数据库的那个sid

2.输入 sqlplus /nolog

3.将数据库启动到RESTRICTED模式下做字符集更改：

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 236000356 bytes

Fixed Size 451684 bytes

Variable Size 201326592 bytes

Database Buffers 33554432 bytes

Redo Buffers 667648 bytes

Database mounted.

sql>ALTER SYSTEM ENABLE RESTRICTED SESSION;

System altered.

sql>ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;

sql>ALTER SYSTEM SET AQ_TM_PROCESSES=0;

sql>alter database open;

Database altered.

--修改为中文字符集

sql>ALTER DATABASE character set INTERNAL_USE ZHS16GBK;

--修改为英文字符集

sql>ALTER DATABASE character set INTERNAL_USE AL32UTF8;

Database altered.

sql>select * from v$nls_parameters;

略

19 rows selected.

重启检查是否更改完成：

sql>startup

Database opened.

sql>select * from v$nls_parameters;