Sql 在内部联接中获得一个值的总和会增加重复的值

我正在运行一个查询，它每月从表中统计记录。 我正在尝试添加一个额外的列，名为“TotalPrice”，我需要“结算”表中所有价格的总和

我面临的问题是由于内部联接，由于内部联接返回的重复记录，价格的“总和”将多个价格相加。有并没有一种方法可以避免这种情况，并从独特的记录中获得价格的总和

SELECT
CONCAT(year(datetime), '-', month(datetime)) AS YearMonth,
COUNT (DISTINCT a.id) AS TOTAL, SUM(total_price) AS TotalPrice
FROM settle AS a with (nolock)
     INNER JOIN transfers b with (nolock) ON b.settleId = a.id 
     INNER JOIN Fdata AS c with (nolock) ON c.id=  b.data 
GROUP BY CONCAT(year(datetime), '-', month(datetime))

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提前感谢。

sql server 2008及以后版本：

with CTE as -- A CTE alows us to manipulate the data before we use it, like a derived table
(
select datetime, id, total_price, 
       row_number() over(partition by id, datetime order by total_price) as rn -- This creates a row number for each combo of id and datetime that appears
FROM settle AS a with (nolock)
     INNER JOIN transfers b with (nolock) ON b.settleId = a.id 
     INNER JOIN Fdata AS c with (nolock) ON c.id=  b.data 
)
SELECT CONCAT(year(datetime), '-', month(datetime)) AS YearMonth,
       COUNT (DISTINCT a.id) AS TOTAL, 
       SUM(total_price) AS TotalPrice
from CTE
where rn = 1 -- that row_number we created? This selects only the first one, removing duplicates
group by CONCAT(year(datetime), '-', month(datetime))

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我假设每个

id

每个

datetime

都有一个

total\u price

？是的，它是一个。。我要一个月的所有总价的总和。。。我不能使用SUM（不同的总价），因为多个记录可能有相同的价格。非常感谢它的有效性，你也能给我解释一下吗？