Linq GroupJoin 使用

备忘:

var data = BoshccEntities.Current.TB_MB_1.GroupJoin(BoshccEntities.Current.TB_MB_2, o => o.HospitalID, m => m.MemberID, (t, m) => new { t, m }).GroupJoin(BoshccEntities.Current.TB_CM_3, o => o.t.ServiceCode, s => s.DicNum, (o, s) => new { t = o.t, m = o.m, s }).GroupJoin(BoshccEntities.Current.TB_CM_3, o => o.t.PaymentMethodCode, p => p.DicNum, (o, p) => new { t = o.t, m = o.m, s = o.s, p }).Where(o =>(isenable.HasValue ? o.t.IsEnable == isenable.Value : true)&& (hasHospital ? hospitalIDs.Contains(o.t.HospitalID) : true)&& (hasService ? o.t.ServiceCode == service : true)&& (hasPayment ? o.t.PaymentMethodCode == payment : true)).OrderBy(o => o.t.ID).Select(o => new{ID = o.t.ID,HospitalID = o.t.HospitalID,ServiceCode = o.t.ServiceCode,PaymentMethodCode = o.t.PaymentMethodCode,IsEnable = o.t.IsEnable,Remark = o.t.Remark,Hospital = o.m.FirstOrDefault(), //关键1Service = o.s.FirstOrDefault(),Payment = o.p.FirstOrDefault()}).ToList() //关键2.Select(o => new TB_MB_4{ID = o.ID,HospitalID = o.HospitalID,ServiceCode = o.ServiceCode,PaymentMethodCode = o.PaymentMethodCode,IsEnable = o.IsEnable,Remark = o.Remark,HospitalName = o.Hospital == null ? "" : o.Hospital.HospitalName, //关键3ServiceName = o.Service == null ? "" : o.Service.DicName,PaymentName = o.Payment == null ? "" : o.Payment.DicName});