oracle characters garbled

Oracle is a widely used relational database management system, but it often encounters garbled characters when storing and processing Chinese characters. This is one of the common problems faced by many Oracle developers and administrators.

Oracle Character Set

Before solving the Oracle garbled problem, we need to understand the concept of Oracle character set. Oracle character set refers to the character encoding method in the database. The character set affects the insertion, query, storage and output of data. Oracle's default character set is US7ASCII, but when processing non-English characters such as Chinese, it is usually necessary to use a wider character set, such as UTF-8 or GB2312.

Causes of garbled characters

Oracle character set mismatch: When the character set used by Oracle is inconsistent with the character set of the actual data, garbled characters will occur. For example, the database uses the UTF-8 character set to store a Japanese text, but when querying, the client uses the GB2312 character set, and the query results will be garbled.

Mixed Chinese and English: When the inserted data contains both Chinese characters and English characters, garbled characters may occur.

Different database connection methods: When using different types of clients to connect to the same database, the output data may be garbled due to client character set mismatch.

Solution

Modify the Oracle character set: In the Oracle database, you can change the default character set by modifying the NLS_CHARACTERSET parameter. Note that modifying the character set requires caution as it may affect the correctness of existing data.

Use transcoding functions: Oracle provides a series of transcoding functions, such as CONVERT, TO_CHAR, TO_NCHAR, etc., which can convert character sets to avoid garbled characters.

Set the character set in the client: In the Oracle client, you can also set the character set to avoid garbled characters. For example, in SQL*Plus, you can use the following command to set the character set:

set NLS_LANG=AMERICAN_AMERICA.ZHS16GBK

Reference

1. Oracle Database Reference 11g Release 2 (11.2), "Specifying a Character Set"
2. Generation and processing of Oracle Chinese garbled characters
3. "Oracle characters Summary of set and character set conversion", inexplicable black

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