修改NLS_CHARACTERSET 字符集

LINUX8.10 + ORACLE 11G数据库，NLS_CHARACTERSET 字符集变成了US7ASCII，要改成AL32UTF8
1. shutdown immediate
2. startup mount
3. ALTER SYSTEM ENABLE restricted SESSION;
4. alter database open;
5. ALTER DATABASE CHARACTER SET INTERNAL_USE AL32UTF8;
6. ALTER SYSTEM DISABLE restricted SESSION;

验证字符集：
select property_name,property_value from database_properties where property_name like '%CHARACTERSET%';

以下是具体操作步骤：
SQL> !cat /etc/redhat-release
Rocky Linux release 8.10 (Green Obsidian)

SQL> select property_name,property_value from database_properties where property_name like '%CHARACTERSET%';

PROPERTY_NAME
--------------------------------------------------------------------------------
PROPERTY_VALUE
--------------------------------------------------------------------------------
NLS_CHARACTERSET
US7ASCII

NLS_NCHAR_CHARACTERSET
AL16UTF16

SQL> aLTER DATABASE CHARACTER SET INTERNAL_USE AL32UTF8;
aLTER DATABASE CHARACTER SET INTERNAL_USE AL32UTF8
*
ERROR at line 1:
ORA-12719: operation requires database is in RESTRICTED mode

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.

Total System Global Area  668082176 bytes
Fixed Size            2256232 bytes
Variable Size          247464600 bytes
Database Buffers      411041792 bytes
Redo Buffers            7319552 bytes
Database mounted.
SQL> ALTER SYSTEM ENABLE restricted SESSION;

System altered.

SQL> alter database open;

Database altered.

SQL> ALTER DATABASE CHARACTER SET INTERNAL_USE AL32UTF8;

Database altered.

SQL> select property_name,property_value from database_properties where property_name like '%CHARACTERSET%';

PROPERTY_NAME
------------------------------
PROPERTY_VALUE
--------------------------------------------------------------------------------
NLS_CHARACTERSET
AL32UTF8

NLS_NCHAR_CHARACTERSET
AL16UTF16

SQL> ALTER SYSTEM DISABLE restricted SESSION;

System altered.