Oracle 10g Character Set problem __oracle

1. Problem: My computer is not installed oracle10g server, installed oracle10g client, and then there is a free version of the Pl/sql, the use of Sqlplus, you can log on normally, do not appear the client and database character sets inconsistent problems, When I first logged in using Pl/sql, there was an inconsistency between the database and the client character set, as shown in the following illustration:

2. Solution:
Search on Google, Basically all answer are: Start-run-regedit-find the hint path-find the Nls_lang key, his value is: Simplified Chinese_china. ZHS16GBK, modified to: simplified Chinese_china. al32utf8-Login pl/sql-problem is resolved, I also follow this step to do, but I found the path above software, but the following does not exist, after a few attempts to finally find a solution to solve the Pl/sql first logon character set inconsistency problem.

Sql>conn as/sysdba
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;
ORA-12712: The new character set must be a superset of the old character set
----Then we can skip the check of the superset to make changes:
sql> ALTER DATABASE character set Internal_use ZHS16GBK;
--we see that this process is exactly the same as the internal process of an ALTER DATABASE CHARACTER set operation, meaning that the help that Internal_use provides is that the Oracle database bypasses the checksum of subsets and superset.
Sql> select * from V$nls_parameters; 
sql> shutdown immediate;
sql> Startup
sql> select * from V$nls_parameters;

Finally reopen the Pl/sql will not appear the message that the character set is inconsistent.
3. The reasons for the above problems: I probably summed up a bit, because I used to install oracle11g, on my Computer, also appeared this problem, seemingly did not solve, the last uninstall, the registry also deleted, but did not know that the deletion of completely incomplete, It is possible that the installation did not choose a custom installation at the time, so it should be noted later that this is not a problem with correcting the client character set, but rather that the database character set should be modified.
PS: These are the problems and solutions that I have encountered today.