Question

SHOPS
+----+------------+
| id | shop_name  |
+----+------------+

ORDERBOOKINGS
+-----+---------+-------------+------------+
| id  | shop_id | grand_total | created_at |
+-----+---------+-------------+------------+

我想得到一张这样的表：

+------------+--------------+--------------+
| shop_name  | total_orders | total_amount |
+------------+--------------+--------------+

条件是我有日期过滤器，它只返回指定日期之间的订单总数。我想要它返回所有的商店（如果这些日期之间没有一些商店的订单那么它应该返回那些total_orders为0）。

注意：有些商店甚至可能没有订单表中的条目。

我尝试过以下操作，但无法从商店表中返回所有行：

SELECT COUNT(orderbookings.id),
       SUM(orderbookings.grand_total),
       shops.shop_name
FROM `orderbookings`
LEFT JOIN shops
    on orderbookings.shop_id = shops.id
where orderbookings.created_at BETWEEN "2015-10-22 17:02:02" AND "2017-03-07 17:02:02"
GROUP BY shops.id

我知道如何实现这一目标。

感谢。

Answer 1

将where替换为查询中的and，将LEFT JOIN替换为RIGHT JOIN：

SELECT
    COUNT(orderbookings.id),
    COALESCE(SUM(orderbookings.grand_total), 0),
    shops.shop_name 
FROM `orderbookings` 
RIHGT JOIN shops on orderbookings.shop_id = shops.id and orderbookings.created_at BETWEEN "2015-10-22 17:02:02" AND "2017-03-07 17:02:02" 
GROUP BY shops.id

说明：
1）如果你想获得所有的商店，你应该使用shops作为主表，然后离开加入orderbookings，在这里我使用正确的加入，因为你使用orderbookings作为主表; <登记/> 2）如果您使用orderbookings中的where列，则左连接将作为内部联接。

最后，left join解决方案会这样：

SELECT
    COUNT(orderbookings.id),
    COALESCE(SUM(orderbookings.grand_total), 0),
    shops.shop_name 
FROM `shops ` 
LEFT JOIN orderbookings on orderbookings.shop_id = shops.id and orderbookings.created_at BETWEEN "2015-10-22 17:02:02" AND "2017-03-07 17:02:02" 
GROUP BY shops.id

Answer 2

您想要撤消您的加入并添加一些IFNULL：

SELECT IFNULL(COUNT(orderbookings.id),0),
       IFNULL(SUM(orderbookings.grand_total),0),
       shops.shop_name
FROM `orderbookings`
RIGHT OUTER JOIN shops
    on orderbookings.shop_id = shops.id
       and orderbookings.created_at BETWEEN "2015-10-22 17:02:02" AND "2017-03-07 17:02:02"
GROUP BY shops.id

mySQL在右表上保持连接（无行）条件

2 个答案: