oracle修改“NLS_NCHAR_CHARACTERSET”字符集

测试数据库的NLS_NCHAR_CHARACTERSET和正式环境不一致，需要由UTF8修改为AL16UTF16。

1、停数据库

SQL> alter system checkpoint;

System altered.

SQL> alter system checkpoint;

System altered.

SQL> alter system switch logfile;

System altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

 

2、启动数据库
SQL> STARTUP MOUNT EXCLUSIVE;
ORACLE instance started.

Total System Global Area  838860800 bytes
Fixed Size                  2024536 bytes
Variable Size             192940968 bytes
Database Buffers          637534208 bytes
Redo Buffers                6361088 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 NATIONAL CHARACTER SET INTERNAL_USE AL16UTF16;

Database altered.

注意：

1）这样修改会影响数据库中定义了Nclob、NVARCHAR2等大字段的表，会出现乱码。需要重新导入表，当然在修改前要备份相关表。

2）如果没有大对象，在使用过程中进行语言转换没有什么影响，（切记设定的字符集必须是ORACLE支持，不然不能start）

若直接运行

ALTER DATABASE NATIONAL CHARACTER SET AL16UTF16;

也可以,但是可能会出现‘ORA-12717: Cannot ALTER DATABASE NATIONAL CHARACTER SET when
NCLOB data exists’ 这样的提示信息

报错信息如下：

Wed May 30 16:25:58 2012
alter database national character set AL16UTF16
Wed May 30 16:25:58 2012
 XDB.XDB$NMSPC_ID (NMSPCURI) - NVARCHAR2 populated
ORA-12717 signalled during: alter database national character set AL16UTF16...

 

3、在停数据库时hang住了，没有办法只有直接abort了再startup。

SQL> shutdown immediate;
ORA-03113: end-of-file on communication channel

SQL> exit

 

SQL> connect /as sysdba
Connected to an idle instance.
SQL> shutdown abort;
ORACLE instance shut down.
SQL> exit