How to view Oracle Character Set Modification

1. How to view the database Character Set
[A] database server Character Set select * from nls_database_parameters, which is derived from props $ and indicates the character set of the database.
Client Character Set environment 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 in the session Character Set environment, which is derived from v $ nls_parameters, indicating the session's own settings, which may be the session environment variable or the session is completed by alter session. 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.
2. How to modify the character set
[A] version 8i and later can use alter database to modify the character set, but it is also limited to 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; Feedom.net, the earliest website administrator in China
Alter system enable restricted session;
Alter system set job_queue_process = 0;
Alter database open;
Alter database character set zhs16gbk;