检索一行不重复MySQL

Question

我是mySQL的新手，请求帮助。我有一个sales_flat_order列，用于保存来自多个客户的订单以及sales_flat_order_status_history表，用于保存每个订单的评论（如待处理，已验证，完成等）。我正在尝试合并这两个表，但只返回订单号，我只选择已验证的最小值（状态）。但是，当我运行我的代码时，我得到重复请求我需要帮助。请参阅下面的代码。请帮忙。

SELECT DISTINCT sales_flat_order.customer_id,  
MIN(sales_flat_order_status_history.entity_id) AS  
entity_id,sales_flat_order_status_history.parent_id,
sales_flat_order_status_history.created_at AS order_date 
FROM sales_flat_order LEFT JOIN sales_flat_order_status_history 
ON sales_flat_order_status_history.parent_id = sales_flat_order.entity_id
LEFT JOIN (SELECT customer_id FROM sales_flat_order  
       LEFT JOIN sales_flat_order_status_history ON 
sales_flat_order_status_history.parent_id = sales_flat_order.entity_id
       WHERE sales_flat_order.created_at < '2013-11-30 23:00:00') AS oo ON   
oo.customer_id=sales_flat_order.customer_id
WHERE ((sales_flat_order_status_history.status LIKE '%verified%' AND  
sales_flat_order.created_at > '2013-11-01 00:00:00')
OR (sales_flat_order.status LIKE '%complete%' AND sales_flat_order.created_at < '2013- 11-01 00:00:00')) 
AND sales_flat_order_status_history.created_at >= '2013-11-30 23:00:00'
AND sales_flat_order_status_history.created_at <= '2013-12-31 22:59:59'  
AND sales_flat_order.customer_id IS NOT NULL 
AND oo.customer_id IS NULL
GROUP BY sales_flat_order.entity_id