SELECT nom_pays, COUNT(c.numero_commande) FROM commandes c JOIN clients cl ON (c.client_id = cl.client_id) JOIN contacts co ON (cl.contact_id = co.contact_id) JOIN pays p ON (co.code_pays = p.code_pays) WHERE date_commande BETWEEN to_date('01/01/2011', 'DD/MM/YYYY') AND to_date('31/12/2011', 'DD/MM/YYYY') GROUP BY p.nom_pays ORDER BY COUNT(c.numero_commande) DESC LIMIT 1;
