[sql] select MAX data

[optime]

select 
   t1.id, t1.idcliente, t1.data 
from contatti t1 JOIN (
   select distinct
      contatti.idcliente AS idcliente,
      max(contatti.data) AS data
   from 
      contatti
   group by
      contatti.idcliente) T2
ON t1.idcliente=t2.idcliente AND t1.data=t2.data