LINQ的查询语法-实现左连接

var data = from b in body
                           join m in member on b.MemberID equals m.MemberID into um
                           from m in um.DefaultIfEmpty()
                           join w in warehouse on b.WarehouseID equals w.WarehouseID into uw
                           from w in uw.DefaultIfEmpty()
                           join wi in interfacewarehouse on b.InterfaceWarehouseID equals wi.WarehouseID into uwi
                           from wi in uwi.DefaultIfEmpty()
                           join u in user on b.DealBy equals u.UserID into us
                           from u in us.DefaultIfEmpty()
                           select new
                           {
                               b.AbnormalMonitoringID,
                               b.AbnormalMonitoringCode,
                               b.CreateDate,
                               b.DealBy,
                               b.DealDate,                               
                               b.OrderStatus,
                               b.OrderStatusName,
                               b.ReceiveDate,
                               b.TaskType,
                               b.TaskTypeName,
                               b.Memo,
                               b.OverTime,
                               MemberNo= m != null ? m.MemberNo:"",
                               MemberName = m != null ? m.MemberName : "",
                               WareHouseName = w != null ? w.WareHouseName : "",     
                               InterfaceWarehouseName= wi != null? wi.WareHouseName : "",
                               DealName= u != null ? u.UserName : "",                                                             
                           };