LINQ to SQL with group by clause with aggregate function

Question

I need equivalent LINQ to SQL query for the query written in access database. Below is the query in access database.

SELECT  Table1.ID, Table1.CODE, MIN (Table1.COST) 
FROM Table1 GROUP BY Table1.ID, Table1.CODE

In this query I get COST which is minimum to the given repeated CODE

Below query is giving error "Invalid anonymous type member declarator. Anonymous type members must be declared with a member assignment, simple name or member access."

var ptQ = from i in
(from uh in ptTable
 select new
 {
     uh.ID, uh.CODE, uh.COST
 })

group i by new { i.ID, i.CODE }
into g

select new
{
    g.Key.ID, g.Key.CODE, g.Min(uh => uh.COST)
};

Answer 1

You need to specify the property name for the Min call:

select new {g.Key.ID, g.Key.CODE, MinimumCost = g.Min(uh=>uh.COST)};

The C# compiler will infer a name if the property value is a property or field access (as per ID and CODE), so the above is equivalent to:

select new { ID = g.Key.ID,
             CODE = g.Key.CODE,
             MinimumCost = g.Min(uh=>uh.COST) };

Personally I would specify the names everywhere if they're not idiomatic C# names otherwise:

select new { Id = g.Key.ID,
             Code = g.Key.CODE,
             MinimumCost = g.Min(uh=>uh.COST) };

Answer 2

You need to tell it what to call the last value in the anon-type (note that for direct member access members (g.Key.ID and g.Key.CODE) the name can be inferred (ID and CODE respectively):

select new {g.Key.ID, g.Key.CODE, MinCost = g.Min(uh=>uh.COST)};

You can also supply explicit names for the other members if you want:

select new {Id = g.Key.ID, Code = g.Key.CODE, MinCost = g.Min(uh=>uh.COST)};

Answer 3

You should be able to do it in one statement:

from i in Table1
group i by new { i.ID, i.CODE } into g
select new { g.Key.ID, g.Key.CODE, COST = g.Min(x => x.COST) }