max（date_field）を持つIDでグループ化

ここでは、最新のdate_addを取得するサブクエリが必要です。 すべてのid_order テーブルps_order_history 。サブクエリの結果は、元のテーブルps_order_historyに結合されます。 date_addの2つの列でmacthする場合： およびid_order 。

SELECT  c.firstname, 
        c.lastname, 
        d.product_name, 
        o.payment, 
        s.name, 
        h.date_add
FROM    ps_orders o
        INNER JOIN ps_order_detail d ON d.id_order = o.id_order
        INNER JOIN ps_customer c ON c.id_customer = o.id_customer
        INNER JOIN ps_order_history h ON o.id_order = h.id_order
        INNER JOIN  
        (
            SELECT  id_order, MAX(date_add) max_date
            FROM    ps_order_history
            GROUP   BY id_order
        ) x ON  h.id_order = x.id_order AND
                h.date_add = x.max_date
        INNER JOIN ps_order_state_lang s ON s.id_order_state = h.id_order_state
WHERE   s.id_lang =6
GROUP   BY c.id_customer