mysql - UPDATE riga basata su altre righe

Certo, puoi farlo in una query. Utilizzando questa tabella di esempio:

create table duotri (time varchar(100), type int, genre int, doubles int, triples int);
insert duotri values
('2010.06.21 12:00'    ,1        ,1        ,0            ,0),
('2010.06.21 12:00'    ,1        ,2        ,0            ,0),
('2010.06.21 12:00'    ,1        ,1        ,0            ,0),
('2010.06.21 12:00'    ,2        ,3        ,0            ,0),
('2010.06.22 12:00'    ,2        ,2        ,0            ,0),
('2010.06.22 12:00'    ,2        ,3        ,0            ,0),
('2010.06.22 12:00'    ,1        ,1        ,0            ,0);

La dichiarazione di aggiornamento dovrebbe unirsi al modulo GROUPed per ottenere i doppi e i tripli.

update duotri t1
inner join (
    select time, type,
     case when count(distinct genre) = 2 then 1 else 0 end doubles,
     case when count(distinct genre) = 3 then 1 else 0 end triples
    from duotri
    group by time, type) t2
   on t1.time=t2.time and t1.type=t2.type
set t1.doubles=t2.doubles, t1.triples = t2.triples;