var Query=from t in table
    group t by t.name
    select new{name=g.key,a=g.sum(v=>v.a),b=g.sum(v=>v.b),.....}

------解决方案--------------------

var re = from t in datatable 
        group t by new {t.a,
                        t.b,
                        t.c,
                        t.d} into g
        select new {g.key,
                    e=g.Sum(k => k.a)};


------解决方案--------------------

var table = from t in _dt3.AsEnumerable()
 group t by t.Field<string>("Name0") into s
 select new
 { 
 Name0 = s.Key,
 Name1 = s.Sum(v => v.Field<string>("Name1")),
 Name2 = s.Sum(v => v.Field<string>("Name2")),
 Name3 = s.Sum(v => v.Field<string>("Name3")),
 Name4 = s.Sum(v => v.Field<string>("Name4")),
 Name5 = s.Sum(v => v.Field<string>("Name5")),
 Name6 = s.Sum(v => v.Field<string>("Name6")),
 Name7 = s.Sum(v => v.Field<string>("Name7"))
 };