每个一对多关系ID一次SQL SUM列值

Question

我有一张类似于下面的表格叫做付款。我想运行一个查询，它会给我：

付款次数，OrderAmounts的总和以及TotalPaymentAmount的总和（这里是问题）

--------------------------------------------------
| PaymentID | OrderAmount | TotalPaymentAmount   |
--------------------------------------------------
|      1    |     10      |          10          |
--------------------------------------------------
|      2    |     15      |          25          |
--------------------------------------------------
|      2    |     10      |          25          |
--------------------------------------------------
|      3    |     30      |          125         |
--------------------------------------------------
|      3    |     10      |          125         |
--------------------------------------------------
|      3    |     70      |          125         |
--------------------------------------------------
|      3    |     15      |          125         |
--------------------------------------------------

查询：

SELECT
  COUNT(PaymentID)
  ,SUM(OrderAmount)
  ,SUM(TotalPaymentAmount)
FROM Payment

这会产生：

--------------------------------------------------
| PaymentID | OrderAmount | TotalPaymentAmount   |
--------------------------------------------------
|      7    |     160     |         560          |
--------------------------------------------------

正如您所看到的，并且正如预期的那样，我们对TotalPaymentAmount列中的每个条目都进行了提交，从而产生了提升的数字。相反，我想运行相同的查询，但这一次是每个唯一的paymentID在SUM上的TotalPaymentAmount。

有什么建议吗？

永远感谢你

Answer 1

您需要预先汇总数据：

select sum(numpayments), sum(amount), sum(totalpayments)
from (select p.paymentid, count(*) as numpayments, sum(orderamount) as amount,
             max(TotalPaymentAmount) as totalpayments
      from payment p
      group by p.paymentid
     ) p;

Answer 2

SELECT
  COUNT(PaymentID)
  ,SUM(OrderAmount)
  ,SUM(TotalPaymentAmount)
FROM Payment
group by PaymentID

我认为应该工作。