How to view and modify the Oracle encoding format ____web

--View Oracle database Character set:

Select Userenv (' language ') from dual;

Query results:
　

Simplified Chinese_china.　　Al32utf8
--modifies the Oracle database character set: (In SQL Plus)
sql> conn/as sysdba;
sql> shutdown immediate;
Database closed.
Database dismounted. 
Oracle instance shut down.
sql> startup Mount;
Oracle instance started.
Total system Global Area  135337420 bytes
fixedsize 452044 bytes variablesize 109051904 bytes
dat　　Abasebuffers 25165824 bytes
redobuffers 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/ZHS16GBK
sql> shutdown;
Sql> startup;