Använd kommandot mysql GROUP BY. Helt oprövat kodexempel:
select sum(x) as "sum", date as "date" from (
select distinct a.id as ID, a.dur as x, DATE(FROM_UNIXTIME(rtime)) as date from b_c
inner join c on b_c.c_id = c.id
inner join a on c.id = a.c_id
inner join a_au on a.id = a_aud.id
inner join d on a_au.rev = d.rev
where
b_c.b_id = 30 and
a_au.stat != 1
) AS SubSelectTable
group by date;
Se:http://dev.mysql.com /doc/refman/5.0/en/group-by-functions.html