plsql 登录后，提示数据库字符集（AL32UTF8）和客户端字符集（ZHS16GBK）不一致,PL/SQL database character set(AL32UTF8) and Client character set(ZHS16GBK) are different

原文网址：http://blog.163.com/magicc_love/blog/static/18585366220123111128283/

启动PL/SQL Developer 报字符编码不一致错误

Database character set (AL32UTF8) and Client character set (ZHS16GBK) are different.
Character set conversion may cause unexpected results.

Note: you can set the client character set through the NLS_LANG environment variable or the NLS_LANG registry key in

HKEY_LOCAL_MACHINESOFTWAREORACLEKEY_Oracle_10g.

打开注册表,通过命令regedit。找到到文中提示的路径，发现NLS_LANG键的值为:

SIMPLIFIED CHINESE_CHINA.ZHS16GBK

修改为：SIMPLIFIED CHINESE_CHINA.AL32UTF8

还有一种可能是由于安装11g的时候没选择自定义安装造成的

打开plsql，执行以下代码：
SQL> conn /as sysdba
SQL> shutdown immediate;
SQL> startup mount
SQL> ALTER SYSTEM ENABLE RESTRICTED SESSION;
SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;
SQL> ALTER SYSTEM SET AQ_TM_PROCESSES=0;
SQL> alter database open;
SQL> ALTER DATABASE CHARACTER SET ZHS16GBK;
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;
--我们看到这个过程和之前ALTER DATABASE CHARACTER SET操作的内部过程是完全相同的，也就是说INTERNAL_USE提供的帮助就是使Oracle数据库绕过了子集与超集的校验.
SQL> select * from v$nls_parameters; 
SQL> shutdown immediate;
SQL> startup
SQL> select * from v$nls_parameters;