1. Oracle 11g卸载

网上教程
暂且只参照网络教程，等自己发现点特别的方法之后再做补充。

2. PL/SQL Developer出现乱码

首先修改Oracle数据库的编码

select userenv('language') from dual;这段代码查询当前字符集

sql> shutdown immediate;

database closed.
database dismounted.
oracle instance shut down.

sql> startup mount;

oracle instance started.
total system global area 135337420 bytes
fixed size 452044 bytes
variable size 109051904 bytes
database buffers 25165824 bytes
redo buffers 667648 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 character set internal_use utf8;
sql> shutdown immediate;
sql> startup;

然后修改PL/SQL Develper的编码

在windows中创 建一个名为“NLS_LANG”的系统环境变量，设置其值为“AMERICAN_AMERICA.UTF8”，然后重新启动 pl/sql developer，这样检索出来的中文内容就不会是乱码了。