LINQ 2 SQL分组问题

我不确定,但是,下面的代码有效吗?

var groups = from p in dc.Pool
             join pm in dc.PoolMembers on p.ID equals pm.PoolID
             group p by p.Group into grp
             select grp.Select(g=> g.ID);

编辑

var groups = from p in dc.Pool
             join pm in dc.PoolMembers on p.ID equals pm.PoolID
             group p by p.Group into grp
             select grp.Select(g=> new{ 
                  Id = g.Id, 
                  GroupName = grp.Key.Name,
                  Contribution = pm.Contribution,
                  GameName = p.GameName, });

我想这就是你要找的

      var groups = from p in dc.Pool
               join pm in dc.PoolMembers on p.ID equals pm.PoolID
               group p by p.Group into grp
               select new { grp.Key.ID, GroupName = grp.Key.Group.Name, grp.Key.GameName }; 

var pools = 
  from p in dc.Pool
  select new
  {
    p.ID,
    GroupName = p.Group.Name,
    Contribution = p.PoolMembers.Sum(pm => pm.Contribution),
    p.GameName
  };