如何排除有相同ID的所有行，如果一列不爲空

Question

我下面的查詢：

select oh.id_order,pc.id_product_comment,od.product_id 
from `ps_order_history` oh 
INNER JOIN `ps_orders` o ON o.id_order = oh.id_order 
INNER JOIN `ps_order_detail` od ON od.id_order = oh.id_order 
LEFT JOIN `ps_product_comment` pc ON pc.`id_customer` = o.`id_customer` AND pc.`id_product` = od.`product_id` 
where oh.`id_order_state` = 2 
AND (oh.date_add < pc.date_add OR pc.date_add IS NULL) 

返回以下結果：

id_order | id_product_comment | product_id 
---------------------------------------------- 
    6    3     6 
    6    NULL    5 
    5    NULL    6 
    5    NULL    5 

我想與id_order排除行6，因爲一個行有一個id_product_comment不爲null。 任何想法？

Answer 1

ok瞭解決方案：使用子查詢

select oh.id_order,pc.id_product_comment,od.product_id 
from `ps_order_history` oh 
INNER JOIN `ps_orders` o ON o.id_order = oh.id_order 
INNER JOIN `ps_order_detail` od ON od.id_order = oh.id_order 
LEFT JOIN `ps_product_comment` pc ON pc.`id_customer` = o.`id_customer` AND pc.`id_product` = od.`product_id` 
where oh.`id_order_state` = 2 
AND (oh.date_add < pc.date_add OR pc.date_add IS NULL) 
GROUP BY oh.id_order 
HAVING pc.id_product_comment IS NULL 

Answer 2

解。子查詢將獲得ps_product_comment上包含任何條目的id_order列表。這是左連接到主查詢，然後WHERE子句檢查沒有匹配的記錄。

SELECT oh.id_order, 
     pc.id_product_comment, 
     od.product_id 
FROM `ps_order_history` oh 
INNER JOIN `ps_orders` o ON o.id_order = oh.id_order 
INNER JOIN `ps_order_detail` od ON od.id_order = oh.id_order 
LEFT OUTER JOIN `ps_product_comment` pc ON pc.`id_customer` = o.`id_customer` AND pc.`id_product` = od.`product_id` 
LEFT OUTER JOIN 
(
    SELECT o.id_order 
    FROM ps_orders` o 
    INNER JOIN `ps_order_detail` od ON od.id_order = o.id_order 
    INNER JOIN `ps_product_comment` pc ON pc.`id_customer` = o.`id_customer` AND pc.`id_product` = od.`product_id` 
) sub0 
ON sub0.id_order = oh.id_order 
WHERE oh.`id_order_state` = 2 
AND (oh.date_add < pc.date_add 
OR pc.date_add IS NULL) 
AND sub0.id_order IS NULL