LINQ: Using INNER JOIN, Group and SUM

Question

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.

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

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!

Answer 1

Try this:

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)              }; 

Answer 2

For me (using 4.0), the following works.

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)              };