left join查询慢的问题解决

SELECT *
FROM wx_member_order_info t
LEFT JOIN u_member_info f ON 	t.`member_id` = f.`member_id`
LEFT JOIN wx_gift_order e ON 	t.`id` = e.`order_id`
LEFT JOIN wx_gift_info w ON  e.`gift_id` = w.`id`
LEFT JOIN wx_gift_class c ON   w.`class_id` = c.`id`



e.`order_id` 建立索引 解决