codice:
select *,
case when year(data_ordine) = 2007 then sum(totale) else 0 end as '2007',
case when year(data_ordine) = 2008 then sum(totale) else 0 end as '2008',
case when year(data_ordine) = 2009 then sum(totale) else 0 end as '2009'
....
....
GROUP BY c.cust_id,year(data_ordine)