SQL - 子查询的总和：我做错了什么？

Question

我对 SQL 很陌生，几天前就开始了我的第一步。但要知道我已经走到了死角。如果你愿意帮助我，那就太好了。

这些是必需的表格：

表格：Customer_Bonus
Bonus_ID、Customer_ID、金额
301、100215、100
302、100924、50
...

表：Customer_Mapping
Customer_ID、Name、Adress_ID
100215, 美国能源部工业公司, 8203351
100924, 艾尔卡彭服务有限公司, 849215
...

表格：Customer_Bonus_to_Invoice
Invoice_IDNR、Bonus_ID、金额
216523、301、10
...
244854、302、10
...
284111、301、10
...
299569、302、20
...
316017、302、10
...

我要回答的问题：如何获得所有已用奖金的总和？

这就是我想要的
Customer_ID、姓名、Bonus_ID、奖金总额、已用奖金总额
100215, 美国能源部工业公司, 301, 100, 20
100924, Al Capone Service Ltd., 302, 50, 40
...

这是我一直在尝试的

SELECT 
Customer_Mapping.Customer_ID
Customer_Mapping.Name,
Customer_Bonus.Bonus_ID,
Customer_Bonus.Amount,
(SELECT 
SUM(Customer_Bonus_to_Invoice.Amount) 
FROM Customer_Bonus_to_Invoice 
WHERE Customer_Bonus_to_Invoice.Bonus_ID = Customer_Bonus.Bonus_ID) 
AS 'sum of used bonus'

FROM 
Customer_Bonus
Customer_Mapping
Customer_Bonus_to_Invoice 

WHERE
Customer_Bonus.Customer_ID = Customer_Mapping.Customer_ID

这是 JOIN 的工作吗？

Answer 1

给你：

SELECT CM.CUSTOMER_ID,
    CM.NAME ,
    CB.Bonus_ID,
    cb.Amount,
    SUM(cbi.Amount)
FROM CUSTOMER_MAPPING CM
INNER JOIN CUSTOMER_BONUS CB
ON CM.CUSTOMER_ID=CB.CUSTOMER_ID
INNER JOIN CUSTOMER_BONUS_TO_INVOICE CBI
ON cbi.Bonus_ID=cb.Bonus_ID
GROUP BY CM.CUSTOMER_ID,
    CM.NAME,
    CB.BONUS_ID,
    cb.Amount;

Answer 2

试试这个：

SELECT t1.Customer_ID,t1.Name,sum(t2.Amount) as    total_sum_of_bonus,sum(t3.Amount) as sum_of_used_bonus FROM Customer_Mapping as t1
LEFT JOIN Customer_Bonus as t2 on t1.Customer_ID=t2.Customer_ID
LEFT JOIN Customer_Bonus_to_Invoice as t3 on t2.Bonus_ID=t3.Bonus_ID
GROUP BY t1.Customer_ID,t1.Name,t3.Bonus_ID