
Bon j'ai trouvé la solution mais c'est trop lent.
SELECT substring( t1.`start_time` , 1, 10 ) , t1.`seizure_traffic` , t1.`avail_circuit_num` , t1.`seizure_traffic` / t1.`avail_circuit_num` AS `taux_d_occupation` , `object_instance`
FROM `office_incomming` as t1
WHERE ( t1.`msc_id` =1) AND ( INSTR( t1.`object_instance` , "N1" ) <>0 )
AND (substring( t1.`start_time` , 1, 10 ) BETWEEN "2008-09-03" AND "2008-10-08") AND t1.`seizure_traffic` IN (SELECT MAX(t2.`seizure_traffic`)
FROM `office_incomming` as t2 WHERE ( t2.`msc_id` =1) AND ( INSTR( t2.`object_instance` , "N1" ) <>0 )
AND (substring( t2.`start_time` , 1, 10 ) BETWEEN "2008-09-03" AND "2008-10-08") GROUP BY substring( t2.`start_time` , 1, 10 )
)
Est ce qu'on peut l'optimiser?