linq 分组求和

static void Main()

        {
            DataTable dt =  new  DataTable();
            dt.Columns.Add( "c1" ,  typeof ( int ));
            dt.Columns.Add( "c2" ,  typeof ( string ));
            dt.Columns.Add( "c3" ,  typeof ( int ));


            dt.Rows.Add(1,  "技术部" , 130);
            dt.Rows.Add(2,  "产品部" , 200);

            dt.Rows.Add(3,  "市场部" , 130);
            dt.Rows.Add(3,  "市场部" , 30);

            var query = from d  in  dt.AsEnumerable()
                        group d by d.Field< string >( "c2" ) into g
                        select  new
                        {
                            c2 = g.Key,
                            c3 = g.Sum(t => t.Field< int >( "c3" ))
                        };
            query.ToList().ForEach(q => Console.WriteLine( "{0},{1}" , q.c2, q.c3));
        }