linq增删改查的语法介绍.doc

一课资料网/linq语法应用的很多。下面我将linq增删改查的语法介绍给大家，供大家学习和参考。1.查询语法（分为查询列表和条件查询）A.查询列表public IQueryable getListInfo( HotelDataClasses hoteldata=new HotelDataClasses (;IQueryable fianinfo = from h in hoteldata.Htel_FinancialPayee select new Htel_FinacialPayeeModelFp_ID = h.Fp_ID,Fp_PayeeBank = h.Fp_PayeeBank;if (fianinfo.Count( 0return fianinfo;else return null;B.条件查询，返回MOdel数据集/编辑信息时通过编号查询到的酒店财务收款列表信息public Htel_FinancialPayee GetHtelFinacialInfosByid(long idusing (HotelDataClasses hotelData = new HotelDataClasses(var info = hotelData.Htel_FinancialPayee.Where(P = P.Fp_ID = id.First(;return info;c.多表联合查询语法有2个表的：IQueryable infolist = from h in hoteldata.Htel_FinancialPayee join company in hoteldata.BasCompanyInfo on h.Fp_CompanyId equals company.ID into Cwhere h.Fp_CompanyId = Convert.ToInt32(compnanyid select new Htel_FinacialPayeeModelFp_ID = h.Fp_ID,Companyname = C.First(.CompanyName,Fp_Payee = h.Fp_Payee,Fp_PayeeCard = h.Fp_PayeeCard,Fp_PayeeBank = h.Fp_PayeeBank;return infolist;3个以上的表联合查询IQueryable info = from inf in db.Htel_OrderInfo.Where(P=P.OrderCode=OrderCode join dic in db.Htel_Dictionary on inf.ChannelID equals dic.ID into lfrom y in l.DefaultIfEmpty(from h in db.Htel_Hotelfrom cn in db.Htel_HotelENfrom en in db.Htel_HotelCNfrom ddic in db.Htel_Dictionarywhere inf.MemberID = memberidwhere inf.HotelID = h.IDwhere inf.HotelID = cn.HotelIDwhere inf.HotelID = en.HotelIDwhere inf.PaymentID = ddic.IDselect new ReservationDetailsArrivalTime = inf.ArrivalTime,ChannelID = inf.ChannelID,ChannelName = y.NameCN,CheckIn = inf.Checkin,CheckOut = inf.Checkout,CompanyID = inf.CompanyID,2.修改语法public bool Updateinfo(Htel_FinancialPayee modelHotelDataClasses hoteldata = new HotelDataClasses(;var info = hoteldata.Htel_FinancialPayee.Where(p = p.Fp_ID = model.Fp_ID;if (info.Count( 0Htel_FinancialPayee inf = info.First(;inf.Fp_ID = model.Fp_ID;inf.Fp_Payee = model.Fp_Payee;inf.Fp_PayeeCard = model.Fp_PayeeCard;hoteldata.SubmitChanges(;return true;elsereturn false;3.删除语法public bool delInfo(string id HotelDataClasses hoteldata = new HotelDataClasses(;var info = hoteldata.Htel_FinancialPayee.Where(p = p.Fp_ID = Convert.ToInt32(id .First (;hoteldata.Htel_FinancialPayee.DeleteOnSubmit(info;hoteldata.SubmitChanges(;return true;4.增加语法public bool Addinfo(Htel_FinancialPayee model HotelDataClasses hoteldata = new HotelDataClasses(;Htel_FinancialPayee finamodel = new Htel_FinancialPayee(;finamodel.Fp_Payee = model.Fp_Payee;finamodel.Fp_P