SQL按字段加起來的總和數據

Question

我試圖做一個查詢，獲取總訂單，所有訂單合併的總價格，並將它們按用戶名分組。

我有以下查詢：

SELECT 
    `customers`.`name`   AS 'name', 
    count(`orders`.`id`)  AS 'total orders', 
    sum(`orderDetails`.`price`) AS 'total price' 

FROM `customers` 

INNER JOIN `orders` 
ON 
    `orders`.`customer_id`  = `customers`.`id` 

INNER JOIN `orderDetails` 
ON 
    `orderDetails`.`order_id` = `orders`.`id` 

WHERE 
    `customers`.`company_id` = 1 

GROUP BY 
    `orders`.`id`, -- Removing this will have the users grouped correctly, 
         -- but display an invalid count. 
    `customers`.`id` 

目前我得到的結果類似這樣：

'John', '2', '2.0000' 
'Bill', '3', '3.0000' 
'Bill', '1', '1.0000' 
'John', '2', '2.0000' 
'John', '3', '3.0000' 

當現實：

John has 3 orders with a total price of 7.00 
Bill has 2 orders with a total price of 4.00 

有什麼辦法我可以修復這個？

Answer 1

這裏的問題是，在不同層次的分組。然而，在這種情況下，你可以通過使用count(distinct

select 
    `customers`.`name` as 'name', 
    count(distinct `orders`.`id`) as 'total orders', 
    sum(`orderDetails`.`price`) as 'total price' 
from 
    `customers` 
     inner join 
    `orders` 
     on `orders`.`customer_id` = `customers`.`id` 
     inner join 
    `orderDetails` 
     on `orderDetails`.`order_id` = `orders`.`id` 
where 
    `customers`.`company_id` = 1 
group by 
    `customers`.`id`, 
    `customers`.`name` 

Answer 2

您只需要一組由聲明：

GROUP BY 
`customers`.`name`