Question

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

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.

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

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

Many thanks

Answer 1

Try this :

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

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