Current Users, Session Counts & Authentication Type

SELECT

'Authentication Method'=( CASE WHEN nt_user_name IS not null THEN 'Windows Authentication' ELSE 'SQL Authentication' END), login_name AS 'Login Name', ISNULL(nt_user_name,'-') AS 'Windows Login Name', COUNT(session_id) AS 'Session Count' FROM sys.dm_exec_sessions GROUP BY login_name,nt_user_name