select u.descUserCn as 'Benutzer-ID', FORMAT(s.startTime, 'dd.MM.yyyy HH:mm') as 'Start der Sitzung', FORMAT(s.lastPingTime, 'dd.MM.yyyy HH:mm') as 'Ende der Sitzung' from tblStatsPlatformSessions s join v_Users u on s.user_id = u.intUserCn where u.mandator_id = @current_mandator_id AND (@dateRange_start IS NULL OR s.startTime >= @dateRange_start) AND (@dateRange_end IS NULL OR s.startTime < dateadd(day, 1, @dateRange_end)) order by s.startTime