Question

ORACLE显示中文为乱码。

输入如下语句： select userenv('language') from dual; 结果为：simplified chinese_china.us7ascii。说明安装时字符集设置错了。请问应该怎么修改呢？

Answer 1

在Redhat上安装Oracle 10g没有设定字符集，采用的是操作系统默认字符集：WE8ISO8859P1，将字符集修改为：ZHS16GBK。由于过程不可逆，首先需要备份数据库。
1.数据库全备

2.查询当前字符集
SQL> select * from nls_database_parameters where parameter='NLS_CHARACTERSET';
PARAMETER VALUE
---------------------------------------- ----------------------------------------
NLS_CHARACTERSET WE8ISO8859P1

3.关闭数据库
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

4.启动数据库到mount状态
SQL> startup mount
ORACLE instance started.
Total System Global Area 205520896 bytes
Fixed Size 1266608 bytes
Variable Size 100666448 bytes
Database Buffers 100663296 bytes
Redo Buffers 2924544 bytes
Database mounted.

5.限制session
SQL> alter system enable restricted session;
System altered.

6.查询相关参数并修改
SQL> show parameter job_queue_processes;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
job_queue_processes integer 10

SQL> show parameter aq_tm_processes;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 0

SQL> alter system set job_queue_processes=0;
System altered.

7.打开数据库
SQL> alter database open;
Database altered.

8.修改字符集
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

出现错误提示，新字符集必须是老字符集的超集，也就原来字符集是新字符集的子集，可以再Oracle官方文档上查询字符集包含关系。下面使用Oracle内部命令internal_use，跳过超集检查，生产环境不建议使用此方法。

SQL> alter database character set internal_use ZHS16GBK;
Database altered.

9.查询当前字符集
SQL> select * from nls_database_parameters where parameter='NLS_CHARACTERSET';
PARAMETER VALUE
---------------------------------------- ----------------------------------------
NLS_CHARACTERSET ZHS16GBK

10.关闭数据库
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

11.启动数据库到mount状态
SQL> startup mount
ORACLE instance started.
Total System Global Area 205520896 bytes
Fixed Size 1266608 bytes
Variable Size 100666448 bytes
Database Buffers 100663296 bytes
Redo Buffers 2924544 bytes
Database mounted.

12.将相关参数改回原来值
SQL> alter system set job_queue_processes=10;
System altered.

13.打开数据库
SQL> alter database open;
Database altered.

Answer 2

如果是测试库呢，删掉重建比较好。
不然就手工修改咯，不过要看具体情况咯，一般以下操作就可以啦
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;
SQL>ALTER DATABASE national CHARACTER SET ZHS16GBK;
SQL>SHUTDOWN IMMEDIATE;
SQL>STARTUP

Answer 3

是不是数据库里面的数据的编码不是UTF-8的？