Oracle Character Set Summary (encountered an example: The query result column is titled Chinese characters, but displayed as '? '）

Problem Handling methods:

Query: Select Userenv (' language ') from dual;

Compare the value of the computer environment variable Nls_lang with the query result, if not, modify the computer environment variable Nls_lang

After solving the problem, we summarize the session characters by querying the data:

The character set can be divided into three categories:

1, database server character set;

SELECT * from Nls_database_parameters

The nls_database_parameters is derived from props$ and is the character set that represents the database.

2. Client Character Set Environment

SELECT * from V$nls_parameters;

SELECT USERENV (' language ') from DUAL;

USERENV, V$nls_parameters represents the current character set environment. If you are executing on the client, the client character set environment is represented.

It originates from V$parameter, which represents the setting of the client's character set, which may be a parameter file, an environment variable, or a registry

3. Session Character Set Environment

SELECT * from Nls_session_parameters;

Can be set nls_language= ' Simplified Chinese ' by alter session;

It originates from V$nls_parameters, which represents the session's own settings, either the environment variables of the session or the ALTER session, if there is no special setting for the session, the

Consistent with V$nls_parameters.

The client's character set requires consistency with the server to correctly display non-ASCII characters for the database. If multiple settings exist, ALTER session> environment variable > registry > Parameter File

Character set requirements are consistent, but language settings can be different, language settings are recommended in English. If the character set is ZHS16GBK, then Nls_lang can be AMERICAN_AMERICA.ZHS16GBK.

Oracle Character Set Summary (encountered an example: The query result column is titled Chinese characters, but displayed as '? '）