Linq的LEFT JOIN和RIGHT JOIN方案

Linq只有join，就是inner join啦，只有用如下方案：

var result = from p in snsDC.NT_User
                         join q in snsDC.NT_Photo on p.Portrait equals q.PhotoID into pq
                         from r in pq.DefaultIfEmpty()
                         where userIDs.ToArray().Contains(p.UserID.ToString())
                         select new { p.UserID, p.UserName, r.FilePath };