使用 where 子句的 Linq 多对多查询

Question

我遇到以下问题：我有一些表 "clinic"、"doctor"、"clinicDoctor"（代表多对多的关系），还有 "specialty" 和 "doctorSpecialty"（代表多对多的关系）关系）。我想进行一个 linq 查询，以查找所有拥有特定专业医生的诊所。

在简历中，我想按专业 ID 查找诊所

var clinicLst = (from cli in clinica.Clinic
                                  .Include(x => x.ClinicDoctor) //This is a Collection
                                  .ThenInclude(x => x.IdDoctorNavigation)
                                  .ThenInclude(x => x.DoctorSpecialty) //This is a Collection
                                  .ThenInclude(x => x.IdSpecialtyNavigation)
                                  .Where(cli => (cli.State == true) 
                                  && HERE I WANT THE ESPECIALIDAD.ID == ID BUT I DON'T KNOW HOW)
                                  select cli).ToList();

请多多指教。提前致谢！！！

Answer 1

你的问题不是很清楚，但我认为你正在寻找类似的东西：

var clinicList = await clinica.Clinic.Where(x => x.DoctorSpecialty.Any(s => s.Id == specialtyId)).ToListAsync();

更新

因此 "your question isn't very clear"。通常，对于多对多，尤其是如果您使用的是 EF Core，您应该设置如下：

public class Doctor
{
    ...
    public ICollection<DoctorSpecialty> Specialties { get; set; }
}

public class Specialty
{
    ...
    public ICollection<DoctorSpecialty> Doctors { get; set; }
}

public class DoctorSpecialty
{
    public int DoctorId { get; set; }
    public int SpecialtyId { get; set; }
}

然后，Clinic 会是这样的：

public ICollection<Doctor> Doctors { get; set; }

假设这样设置，那么您将通过以下方式查询：

context.Clinics.Where(x => x.Doctors.Any(d => d.Specialties.Any(s => s.SpecialtyId == specialtyId)))

Answer 2

所以每个诊所都有零个或多个医生，每个医生都在零个或多个诊所工作。显然，您使用的框架使用 virtual ICollection 实现这种多对多关系，就像 Entity Framework 那样。

class Clinic
{
    public int Id {get; set;}  // primary key
    ...                        // other properties

    // every Clinic has zero or more Doctors (many to many):
    public virtual ICollection<Doctor> Doctors {get; set;}
}

同样，医生和专业之间存在多对多关系：

class Doctor
{
    public int Id {get; set;}  // primary key
    ...                        // other properties

    // every Doctor works in zero or more Clinics (many-to-many):
    public virtual ICollection<Clinic> Clinics {get; set;}

    // every Doctor has zero or more Specialties
    public virtual ICollection<Specialty> Specialties {get; set;}
}

为了完整起见，专业：

class Specialty
{
    public int Id {get; set;}  // primary key
    public string Description {get; set;}
    ...                        // other properties

    // every Specialty belongs to zero or more Doctors (many to many):
    public virtual ICollection<Doctor> Doctors {get; set;}
}

I want to make a linq query that find all clinics that have doctors with an especific specialty.

int specialtyId = ...
var clinicsWithSpecialty = myDbContext.Clinics

    // keep only those Clinics that have at least one Doctor with the desired specialty
    .Where(clinic => clinic.Doctors
        .Where(doctor => doctor.Specialties.Select(specialty => specialty.Id == specialtyId)
        .Any())
    .Select(clinic => new
    {
        // Select the clinic properties you want:
        Id = clinic.Id,
        Name = clinic.Name,
        ...

        // Select the Doctors you want:
        Doctors = clinic.Doctorw.Where(doctor => ...)
            .Select(doctor => new
            {
                // Select the Doctor properties that you want
                Id = doctor.Id,
                ...

                Specialties = doctor.Specialties
                    .Where(specialty => ...)
                    .Select(specialty => new
                    {
                        // Select the specialties that you want
                        ...
                    })
                    .ToList(),
             })
             .ToList(),
     });

出于效率原因，不要 select 任何您不打算使用的属性，尤其是连接 table 的外键。如果 Clinic [10] 有 300 名医生，那么每个 Doctor 都将具有相同的结点 table 外键值。不使用这个值，传300次就浪费了

When fetching data, only use Include if you plan to change the fetched data. If you only need to query it, use Select.

使用 where 子句的 Linq 多对多查询

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mysql

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asp.net-core-3.1