Mysql 如何对两个相关表中的列求和

我有两张桌子<代码>发票和

发票项目

。我正在尝试获取每个客户的

总付款

和总

数量

之和。我尝试了以下查询：

SELECT client_id,
sum(total_amount), sum(it.quantity) as days_hired
FROM  `invoices` `iv`
  join invoice_items it on  it.invoice_id=iv.invoice_id
group by client_id, it.invoice_id

但是对于客户id 14，我得到的付款总额是1908，而不是636。看起来此列的总和对于每个发票项都会重复。任何帮助都将不胜感激

invoices

invoice_id    client_id    total_payment
    36        13           530
    38        14           636


invoice_items

invoice_id    user_id      quantity     
36            2            2
38            3            2
38            4            2
38            5            2

预期产出：

13     530       2
14     636       6

你可以在下面试试-

SELECT client_id, sum(total_amount) as toal_amount, sum(it.quantity) as total_quantity
FROM  `invoices` `iv`
join
(
 select invoice_id,sum(quantity) as quantity from invoice_items group by invoice_id
)it on  it.invoice_id=iv.invoice_id
group by client_id, it.invoice_id

你可以在下面试试-

SELECT client_id, sum(total_amount) as toal_amount, sum(it.quantity) as total_quantity
FROM  `invoices` `iv`
join
(
 select invoice_id,sum(quantity) as quantity from invoice_items group by invoice_id
)it on  it.invoice_id=iv.invoice_id
group by client_id, it.invoice_id

尝试：

尝试：

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请发布您的预期输出？您是否也可以更新发票和发票项目表？请发布您的预期输出？您是否也可以更新发票和发票项目表？这似乎有效。我将测试更多的发票。不过还有一个小问题。sum（数量）应该是sum（数量）作为数量。这似乎有效。我将测试更多的发票。不过还有一个小问题。总和（数量）应为总和（数量）作为数量。