>>It's SYSTEM_USER
>
>Sergey,
>
>Thanks for the clarification. Is it System_User because it will also return the Windows logon name if Win authentication is used, whereas Current_User would not?
>
Hi Jon,

With Windows Authentication it'll return DOMAIN\user_login_name, otherwise SQL Server login name. CURRENT_USER, which is equivalent to USER_NAME(), returns database user name which depends on user rights in the current database.