linq sum in vb.net

I need to make a query that look like this is SQL:

SELECT  CodProiect, SUM(Valoare)
FROM DET
WHERE CodProiect = 'cod_pr'
GROUP BY CodProiect;

How can I write the same thing in LINQ?

I have attempted this:

dim gac1 = (From ac1 In t_detalii _
            Where ac1!CodProiect = cod_pr1 _
            Select ac1!Valoare).Sum开发者_开发知识库(Function(ac1) ac1!Valoare)

But it gives me an error "No default member found for type 'Double'."

You need to select ac1 instead of ac1!Valoare (which is the property itself, not the corresponding object)

dim gac1 = (From ac1 In t_detalii _
                       Where ac1!CodProiect = cod_pr1 _
                       Select ac1).Sum(Function(ac1) ac1!Valoare)

edit

You can of course group it in the query already:

dim gac1 = (From ac1 In t_detalii _
                       Where ac1!CodProiect = cod_pr1 _
                       Group By ac1.CodProiect Into ac2
                       Select ac2.Sum(Function(ac2) ac2!Valoare)

(something in that direction, I'm not familiar with the vb.net syntax, also I'm writing it without compilersupport atm.