var ResultDetID = from det in adviceNoteEarnestMoneyTableEntities.PlanModifyApply.Where(PlanModifyApply => PlanModifyApply.ID == 1)
                        join rec in adviceNoteEarnestMoneyTableEntities.PlanModifyRec on det.ID equals rec.ApplyID
                        join draft in adviceNoteEarnestMoneyTableEntities.ContractPlanModifyDraft.Where(t=>t.MType==3) on rec.SubPlanID equals draft.SupPlanID

                        select new
                        {
                            draft.SupPlanID
                        };
这个查出所有要删除的id    要删除这个ContractSubPlan表中含有以上结果集的id   
ContractSubPlan 跟上面可以 的linq也可以通过  SupPlanID 进行关联