LINQ中的简单内部联接 [英] Simple inner join in linq

问题描述

我有三个表A，B和C. C有许多B，其中有许多A.

I have three tables A, B and C. C has many B's which has many A's.

我想将所有这些数据显示在一棵树中，所以我将db.A绑定到了具有三层层次结构的嵌套控件.唯一的问题是我得到的行太多，因为它没有在B和C之间进行内部联接.

I want to display all this data in a tree so I bound db.A to my nested control which had a three layer hierarchy. The only problem is I get too many rows because it's not doing an inner join between B and C.

那么我如何在linq中做这样的事情:

So how can I do something like this in linq:

SELECT A.name, B.name
FROM A
INNER JOIN B ON A.id = B.AID 
INNER JOIN C ON B.id = C.BID
GROUP BY A.Name, B.Name
ORDER BY A.Name

我已经尝试了以下方法:

I've tried the following to no avail:

from a in A
join b in B on a.id equals b.AID
join c in C on b.id equals c.BID
select c

非常感谢

推荐答案

尝试一下:

from a in A 
join b in B on a.id equals b.AID 
join c in C on b.id equals c.BID 
group new {a,b} by new {a.name,b.name} into g
select g

以上联接与您在sql查询中所做的相同，但您想要的是:

Above join is the same as you did in sql query but what you want is :

from a in A 
join b in B on a.id equals b.AID 
join c in C on b.id equals c.BID 
group c by c.name into g
select g

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