Commandes visiteurs pairs 7 derniers jours
SELECT o.id_order,c.id_guest FROM ps_orders o LEFT JOIN ps_cart c ON o.id_cart=c.id_cart WHERE id_guest % 2 = 0 AND o.`date_add` > (NOW() - INTERVAL 1 WEEK)

Commandes visiteurs impairs 7 derniers jours
SELECT o.id_order,c.id_guest FROM ps_orders o LEFT JOIN ps_cart c ON o.id_cart=c.id_cart WHERE id_guest % 2 != 0 AND o.`date_add` > (NOW() - INTERVAL 1 WEEK)