MySQL groupby functions

Great fetaure of MySQL groupby function GROUP_CONCAT

select concat(DATE_FORMAT(date, '%a %d/%m/%Y'),' ',time,';',GROUP_CONCAT(total_gateways SEPARATOR ';'))
from tbl_concurrent_users where company_name = 'rabobank2'
group by date, time,company_server order by date,time

Good link to reference: http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html