//与免打扰中的用户进行比较，筛选出可以正常接收推送的用户
                                var normalReceive = dtUser.AsEnumerable().Except(dtDND.AsEnumerable(), DataRowComparer.Default);

                                //比对两个表的用户名一致的，保存username到list中
                                var intersectUser = dtUserPower.AsEnumerable().Intersect(normalReceive, DataRowComparer.Default);

foreach (var item in intersectUser)
{
   listTemp.Add(item["username"].ToString());
}

  //与免打扰中的用户进行比较，筛选出可以正常接收推送的用户
                                var normalReceive = from r in dtUser.AsEnumerable()
                                                    where
                                                        !(from rr in dtDND.AsEnumerable() select rr.Field<string>("username")).Contains(
                                                        r.Field<string>("username"))
                                                    select r;
                                
                                //比对两个表的用户名一致的，保存token到list中
                                var intersectUser = from r in normalReceive.AsEnumerable()
                                                    where
                                                        (from rr in dtUserPower.AsEnumerable() select rr.Field<string>("username")).Contains(
                                                        r.Field<string>("username"))
                                                    select r;

                                foreach (var item in intersectUser)
                                {
                                    listTemp.Add(item["token"].ToString());
                                }