--execute as login = 'sa';
--execute as user = 'guest';
SELECT @@version
--current context / execute as
, user "user" --same as user_name()
, user_name() "user_name"
, current_user "current_user"
, session_user "session_user"
--current login unless execute as
, system_user "system_user"
, suser_name() "suser_name"
--original context
, ORIGINAL_LOGIN() "original_login"
GO
