查询Linq加入多对多

Question

我正在为我的MVC2应用程序使用Linq-SQL实体.

我有那些表/实体

人(身份证,姓名,姓氏)车(身份证,型号,姓名)经销商(身份证,姓名)

而且我有2到多个表

Persons_Cars(ID,ID_Person,ID_CAR)Persons_Resellers(ID,ID_Person,ID_Reseller)

 public MyModel {

   //Some Fields

    public List<CarPerson> carList;

    public CarPerson 
    {
      String detail;
      int id;
    }
}
 var query=(from person in data.Person

                     join PerCar in data.Persons_Cars on person.ID equals Persons_Cars.ID_Person into JoinedPerCar
                     from PerCar in JoinedPerCar.DefaultIfEmpty()

                     join car in data.car on PerCar .id_car equals car.ID into JoinedCarPe
rson
                     from car in JoinedCarPerson.DefaultIfEmpty()

                     join PerReseller in data.Persons_Resellers on person.ID equals  PerReseller .id_person into JoinedPersReseller 
                     from PerReseller in JoinedPersReseller.DefaultIfEmpty()

                     join Reseller in data.Reseller on PerReseller.id_reseller equals Reseller.ID into JoinedResellerPers
                     from Resller in JoinedFormazioneComp.DefaultIfEmpty()

                     where person.ID_USER == USER.ID 
                     select new MyModel
                                { 
                                     carList = JoinedPerCar.Select(m=>new CarPerson {detail=m.car.Model,id = m.ID}).ToList()},
                                //Other
                                });

我知道这是完全错误的,但我是Linq-SQL的新手我现在遇到了一个问题:

查询有效但我的结果是错误的.事实上,如果一个人有2辆车,我会用2个车辆清单两次收回同一个人.

例

布朗先生有2辆汽车我回收布朗先生--->汽车清单(Car1,Car2)布朗先生--->汽车清单(Car1,Car2)

所以我需要的是,如果一个人有2辆车我只得到1个人用他自己的车的结果

有没有办法更好地编写此查询？怎么能解决我的问题？

谢谢

Answer 1

我认为简单的子查询将完成这项工作(对于经销商而言):

from p in data.Person
select new MyModel {
  carList = (from pc in data.Persons_Cars
             join c in data.car on pc.id_car equals c.ID
             where pc.ID_Person == p.ID 
             select c).ToList()
};

如果您定义了导航属性,那么查询将更加简单(Linq将为您加入):

from p in data.Person
select new MyModel {
   carList = p.Person_Cars.Select(pc => pc.Car).ToList()
};