MySql：从两列不同表中计算的单个查询

Question

我有两张桌子

invoice_tbl

+---+---------+
|id | Amount  |
+---+---------+
|1  | 5000    |
|2  | 3200    |
|3  | 7400    |
+---+---------+

reciept_tbl

+---+-------------+-----------+
|id | invoice_id  |paid_amount|
+---+-------------+-----------+
|1  |      1      | 2000      |
|2  |      1      | 3000      |
|3  |      3      | 6400      |
+---+-------------+-----------+

在上述情况下，我想通过单一查询查找发票余额，以便我可以按余额金额进行缩短。

我赞美你的帮助。

Answer 1

执行GROUP BY计算每个ID的余额sum(i.Amount) - sum(r.paid_amount)。

select i.id, sum(i.Amount) - sum(r.paid_amount) as balance
from invoice_tbl i
    left join reciept_tbl r on i.id = r.invoice_id
group by i.id

执行LEFT JOIN以包含发票而无需任何付款。