注：导入dmp时，常常报ORA-12899错误，其实往往是因为导出和导入的字符集不一致造成的。
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_MACHINE/SOFTWARE/ Oracle /KEY_OraDb11g_home
SIMPLIFIED CHINESE_CHINA.ZHS16GBK 包含 AMERICAN_AMERICA.AL32UTF8.
这可是个麻烦事，不是改客户端字符集的问题。要改 数据库 的字符集：
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;
以后安装oracle11g的时候记得选择自定义安装，把这个字符集的事情事先弄好。
