Oracle modify database character set

1、 Modify database character set , If the logged in client and server are not on the same server , It is suggested that the character sets on both sides should be consistent .
View the client character set ：

select * from v$nls_parameters

NLS_LANGUAGE # typeface
NLS_TERRITORY # region
NLS_CHARACTERSET # Character set
environment variable nls_lang It is composed of these three parts ： typeface region . Character set
such as ：
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
View the server character set ：

select sys_context('userenv', 'language') from dual

2、 Modify client character set
Modify registry ,win+R, Input regedit, Enter the registry ; Find the following path HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\ORACLE\KEY_OraDb11g_home2
（ Be careful ：KEY_OraDb11g_home2 Corresponding to the database you want to modify ）
find NLS_LANG,

Right click , Modify numerical data , Modify to client / The character set corresponding to the server （ Use the first step to query ）; preservation , close .
3、 Change the server-side character set
Get into oracle Of sqlplus window , Sign in dba;
conn user name as sysdba
Enter the following commands in turn ：

shutdown immediate; # stop it database
startup mount;   # Reopen database
alter system enable restricted session;
alter system set job_queue_processes=0;
alter system set aq_tm_processes=0;
alter database open;
alter database character set utf8;
alter database character set internal_use utf8; # Cast encoding format , It may cause the Chinese in the database to become garbled 
shutdown immediate;
>startup;    # restart oracle

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Reference resources ：
https://blog.csdn.net/laukicn/article/details/60962052
https://blog.csdn.net/chenwang2018/article/details/75051482