|IF the session logon is …||THEN …|
|not directory-based||the result value is the session user name.|
|directory-based||If the session maps to a permanent table, the result value is the name of the permanent user.
If the session does not map to a permanent user, the result value is the authcid of the external user.
If you are accessing the Teradata Database through a proxy connection, and you want to get the name of the proxy user, use the CURRENT_USER built-in function.