MySQL的左用（沒有行）連接條件上右表

Question

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

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

我希望得到像這樣的表：

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

的情況是，我有日期過濾器指定之間只返回訂單總額日期。我希望它返回所有商店（如果在這些日期之間沒有一些商店的訂單，那麼它應該將total_orders作爲0返回）。

注意：一些商店可能甚至沒有訂單表中的條目。

我曾嘗試以下，但它無法從商店返回表中的所有行：

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 

任何想法，我怎麼能做到這一點？

謝謝。

Answer 1

更換where到and在您的查詢，LEFT JOIN到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 

說明：
1）如果你想獲得所有的商店，你應該使用shops作爲主表，然後離開加盟orderbookings ，這裏我使用正確的連接，因爲你使用orderbookings作爲主表;
2）如果在where中使用orderbookings的列，則左連接將作爲內連接。

最後，left join解決方案將是這樣的：

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

你想扭轉你的加入，並添加一些IFNULLs：

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