C# LINQ：使用 INNER JOIN、Group 和 SUM
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LINQ: Using INNER JOIN, Group and SUM
提问by Nic
I am trying to perform the following SQL using LINQ and the closest I got was doing cross joins and sum calculations. I know there has to be a better way to write it so I am turning to the stack team for help.
我正在尝试使用 LINQ 执行以下 SQL，我得到的最接近的是进行交叉连接和求和计算。我知道必须有更好的方法来编写它，所以我向堆栈团队寻求帮助。
SELECT T1.Column1, T1.Column2, SUM(T3.Column1) AS Amount
FROM T1
INNER JOIN T2
ON T1.T1ID = T2.T1ID
INNER JOIN T3
ON T2.T3ID = T3.T3ID
GROUP BY T1.Column1, T1.Column2
What I have been trying is the following LINQ code
我一直在尝试的是以下 LINQ 代码
var qTotal = from T2 in context.T2
from T3 in context.T3
where T3.T3ID == T3.T3ID
group T3 by T2.T1ID into gT2T3
from T1 in context.T1
where gT2T3.Key.Equals(T1.T1ID)
select new { T1.Column1,T1.Column2,Amount = gT2T3.Sum(t => t.Column1)};
I know there has to be a better way to write it, I just do not know how, any help would be great!
我知道必须有更好的方法来编写它，我只是不知道如何，任何帮助都会很棒！
采纳答案by Nick Berardi
Try this:
尝试这个：
var total = from T1 in context.T1
join T2 in context.T2 on T1.T2ID equals T2.T2ID
join T3 in context.T3 on T2.T3ID equals T3.T3ID
group T3 by new { T1.Column1, T1.Column2 } into g
select new {
Column1 = T1.Column1,
Column2 = T2.Column2,
Amount = g.Sum(t3 => t3.Column1)
};
回答by Tun
For me (using 4.0), the following works.
对我来说（使用 4.0），以下工作。
var total = from T1 in context.T1
join T2 in context.T2 on T1.T2ID equals T2.T2ID
join T3 in context.T3 on T2.T3ID equals T3.T3ID
group T3 by new { T1.Column1, T1.Column2 } into g
select new {
Column1 = g.Key.Column1,
Column2 = g.Key.Column2,
Amount = g.Sum(t3 => t3.Column1)
};
回答by Muhammad Awais
Below code is working for me :
下面的代码对我有用：
var credit = (from bm in BulkMessage
join sms in SMS on bm.BulkMessageId equals sms.BulkMessageId
where bm.ProfileId == pid && bm.IsActive == true
group sms by sms.SMSCredit into g
select new { SMSCredits = g.Sum(s => s.SMSCredit) }).FirstOrDefault();
