You can control the session parameter that defines the character set to be used for external representation from within the client application submitting the request. Specifying an alternate character set overrides the default client character set for a session.
For example, in BTEQ you can specify:
.[SET] SESSION CHARSET
to specify the name of a character set for the current session.
If you specify a session character set, make sure that it exactly matches the name of a valid, enabled client character set.
For further information on how to specify a session character set, see the users guide for the particular application.