) View and modify the oracle database Character Set

Q] how to view the database Character Set
[A] select * from
Nls_database_parameters, derived from props $, indicates the character set of the database.
Select * from
Nls_instance_parameters, which is from v $ parameter,
Indicates the character set setting of the client, which may be a parameter file, environment variable, or registry.

Select * from
Nls_session_parameters, which is from v $ nls_parameters, indicates the session's own settings, which may be the session's environment variable or alter
The session is complete. If the session has no special settings, it will be consistent with nls_instance_parameters.

The character set of the client must be the same as that of the server to correctly display non-Ascii characters of the database. If multiple settings exist, alter
Session> environment variable> registry> parameter file

The character set must be consistent, but the language settings can be different. We recommend that you use English for language settings. If the character set is zhs16gbk, The nls_lang can be American_America.zhs16gbk.

[Q] how to modify the character set
[A] For 8i or later versions, you can use alter
Database to modify the character set, but only the subset to the superset. We do not recommend that you modify the props $ table, which may cause serious errors.
Startup nomount;
Alter
Database mount exclusive;
Alter system enable restricted session;
Alter
System set job_queue_process = 0;
Alter database open;
Alter database
Character set zhs16gbk;