Fix Chinese Garbled Text in Oracle SQL*Plus on Windows and Linux

Problem Overview

The author experiences Chinese characters displaying correctly in SQL*Plus on Windows, but appearing as garbled text when using PL/SQL on Windows and when accessing Oracle via SSH on Linux.

1. Verify Oracle Server Character Set

Open a command prompt and run the following query:

SQL> select userenv('language') from dual; Result: AMERICAN_AMERICA.ZHS16GBK

An illustration of the query output is shown in the first image.

2. Configure PL/SQL Client Encoding on Windows

Set the NLS_LANG system environment variable to match the server encoding:

Variable name: NLS_LANG Variable value: SIMPLIFIED CHINESE_CHINA.ZHS16GBK The setting is shown in the second image.

3. Verify Linux Client Encoding

On the Oracle server, check the profile files:

vim /home/oracle/.bash_profile Typical entries: export LANG=en_US.gbk export NLS_LANG=AMERICAN_AMERICA.ZHS16GBK

Run the same select userenv('language') query on Linux; it also returns AMERICAN_AMERICA.ZHS16GBK, but Chinese text is still garbled.

4. Adjust Terminal Encoding (Xshell)

The Xshell terminal window was defaulting to UTF‑8, which conflicted with the GBK‑encoded data. Changing the terminal’s character set to GBK (or the system’s default language setting) resolves the display issue.

Conclusion

Correct Chinese display in Oracle requires that the client’s character set (SQL*Plus, PL/SQL, SSH terminal) matches the server’s AMERICAN_AMERICA.ZHS16GBK setting. Adjusting NLS_LANG on Windows and ensuring the Linux terminal uses GBK eliminates the garbled output.