Linq To List Group 和Sum的联合 用法

private void Sum()

{

List<Test> TT = new List<Test>();

TT.Add(new Test { ID = 1, IDName = "Test", ParentID = 0 });

TT.Add(new Test { ID = 2, IDName = "Test", ParentID = 1 });

TT.Add(new Test { ID = 3, IDName = "Test", ParentID = 1 });

TT.Add(new Test { ID = 4, IDName = "Test1", ParentID = 2 });

TT.Add(new Test { ID = 5, IDName = "Test1", ParentID = 2 });

TT.Add(new Test { ID = 6, IDName = "Test1", ParentID = 3 });

var query = from l in TT

group l by new { l.IDName } into g

select new

{

ID = g.Sum(a => a.ID),

IDName = g.Key.IDName

};

}