修改oracle字符集将字符编码WE8MSWIN1252修改为AL32UTF8

本方法根据我目前掌握的知识只能应用于新库，有数据的库不建议使用

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

Total System Global Area  918618112 bytes
Fixed Size          2258640 bytes
Variable Size         549456176 bytes
Database Buffers      360710144 bytes
Redo Buffers            6193152 bytes
Database mounted.
SQL> alter session set sql_trace=true;

Session altered.

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 character set INTERNAL_USE UTF8;

Database altered.

SQL> update props$ set VALUE$='UTF8' where NAME='NLS_NCHAR_CHARACTERSET';

1 row updated.

SQL> commit ;

Commit complete.

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

Total System Global Area  918618112 bytes
Fixed Size          2258640 bytes
Variable Size         549456176 bytes
Database Buffers      360710144 bytes
Redo Buffers            6193152 bytes
Database mounted.
Database opened.
SQL> show parameter undo_undo_retention
SQL> show parameter undo_retention

数据库字符集验证：