NLS_CHARACTERSET in nls_session_parameters returns None

Question

An application I'm using with Oracle seems to be having issues with characters, and I ran the queries below to check on the CHARACTERSET.

• SELECT * FROM nls_session_parameters WHERE PARAMETER='NLS_CHARACTERSET';
• SELECT * FROM nls_database_parameters WHERE PARAMETER='NLS_CHARACTERSET';

The second query from nls_database_parameters returns AL32UTF8.

But the first query seems to return None.

I've read that the nls_session_parameters takes precedence over the nls_database_parameters, but in this case, where there does not seem to be any value set for it, would it fall back to the nls_database_parameters, or is there something that needs to be configured to set the nls_session_parameters.

Thank you for any input on this.

Answer 1

The NLS_CHARACTERSET is the character set which is used by the database. Your session (i.e. the client) does not store anything, thus NLS_CHARACTERSET does not exist.

I assume you are looking for NLS_LANG which tells the database which character set is used by the client. You cannot query NLS_LANG from any database view/table, you have to check settings in your client. You can set NLS_LANG only at your client side, not at database side.

Note, some clients (e.g. Java JDBC based clients) do not use NLS_LANG setting, they use a different globalization mechanism.

Answer 2

From Oracle Docs

NLS_SESSION_PARAMETERS shows the NLS parameters and their values for the session that is querying the view. It does not show information about the character set.

Basically NLS_SESSION_PARAMETERS will not have Parameter called NLS_CHARACTERSET.

The character set is part of the locale, which is determined by the value of NLS_LANG.

NLS_LANG is set as an environment variable on UNIX platforms. NLS_LANG is set in the registry on Windows platforms.

Hence check the NLS_LANG. Also this information is picked up by the client application at startup time, and cannot be changed from within.