plsql data Chinese garbled

1. Log in to plsql, execute sql statement, the output Chinese title is displayed as a question mark????; if the condition contains Chinese, no data is output

    

   

2.  Enter the sql statement select * from V$NLS_PARAMETERS to view the character set and check whether the value of the first line is Simplified Chinese

   

3.  Enter the registry, click HKEY_LOCAL_MACHINE --->SOFTWARE ---> ORACLE--->home (the editor installs Oracle 11g, which is displayed as KEY_OraDb11g_home1), find NLS_LANG, and check whether the value data is: SIMPLIFIED CHINESE_CHINA. ZHS16GBK

   

4.  If there is no problem with the above settings, check the environment variable settings to see if there is a variable NLS_LANG, if not, create a new variable

   

   

   

5.  Create a new variable, set variable name: NLS_LANG, variable value: SIMPLIFIED CHINESE_CHINA.ZHS16GBK, just confirm

   

6.  Exit plsql and log in to plsql again. Enter the sql statement and execute it. The Chinese title is finally displayed normally, and data is output.