Question

    var expr = Data.Customers
        .GroupBy(c => c.Country, c => c.Name);

    foreach (IGrouping<Countries, string> customerGroup in expr)
    {                
        Trace.WriteLine("Country: " + customerGroup.Key);
        foreach (var item in customerGroup)
        {
            Trace.WriteLine(item);
        }
        Trace.WriteLine("");
    }

I wish I got following result:

Country: Italy

Paolo
Marco

Country: USA

James
Frank

instead of:

Country: Italy
Paolo
Marco

Country: USA
James
Frank
Frank

If it is possible, please make it using standard LINQ syntax.

Answer 1

If you want to group by multiple keys you have to use an anonymous type:

var expr = Data.Customers 
             .GroupBy(c =>new{c.Country, c.Name}); 

Then you can access expr.Key.Country and expr.Key.Name.