C# C linq到sql组多行

更新：

还有一张叫做位置特殊标志的表格。它将存储的位置ID和特殊标志配对。有必要在变量SpecialSignsLocation中生成结果，并获得以下结果：

    public IEnumerable<KeyValuePair<int, int>> SpecialSignsLocation = new List<KeyValuePair<int, int>>();

   //json result
    ...
        SpecialSigns:  {
                    BodyType:  [1, 2],
                    Hair:  [3, 1, 2],
                    SpecialSignsLocation: [[1,2], [3,5], [4,1]]
                }

    ...

    //query
    SpecialSignsLocation = entity.persons_signs_location
                          .Where(c => c.PersonId == persons.Id)
                          .Select(s => new { s.Location, s.Sign})
                          .ToDictionary(l => l.Location, l => l.Sign)

相反，结果被复制6次

[
    {
        SpecialSigns:  {
            BodyType:  [1, 2],
            Hair:  [3, 1, 2]
        },

        PersonName: "Aaa",
        PersonLastName: "Bbb",
        PersonPatronymic: "Ccc",

    },
{
        SpecialSigns:  {
            BodyType:  [1, 2],
            Hair:  [3, 1, 2]
        },

        PersonName: "Aaa",
        PersonLastName: "Bbb",
        PersonPatronymic: "Ccc"

    },
{
        SpecialSigns:  {
            BodyType:  [1, 2],
            Hair:  [3, 1, 2]
        },

        PersonName: "Aaa",
        PersonLastName: "Bbb",
        PersonPatronymic: "Ccc"

    },
{
        SpecialSigns:  {
            BodyType:  [1, 2],
            Hair:  [3, 1, 2]
        },

        PersonName: "Aaa",
        PersonLastName: "Bbb",
        PersonPatronymic: "Ccc"

    },
{
        SpecialSigns:  {
            BodyType:  [1, 2],
            Hair:  [3, 1, 2]
        },

        PersonName: "Aaa",
        PersonLastName: "Bbb",
        PersonPatronymic: "Ccc"

    },
{
        SpecialSigns:  {
            BodyType:  [1, 2],
            Hair:  [3, 1, 2]
        },

        PersonName: "Aaa",
        PersonLastName: "Bbb",
        PersonPatronymic: "Ccc"

    }
]

---

问题：如何组合特殊标识符，并将它们带到阵列中？

请尝试以下操作。连接导致笛卡尔积

public List<object> GetPerson(int id)
{
  var query = (from persons in entity.persons where persons.Id.Equals(id)

              select new Person
                     {
                         PersonName = persons.PersonName,
                         PersonLastName = persons.PersonLastName,
                         PersonPatronymic = persons.PersonPatronymic,
                         SpecialSigns = new PersonSpecialSigns()
                         {
                             BodyType = entity.persons_signs_body_type
                                              .Where(c => c.PersonId == persons.Id)
                                              .Select(c => c.PersonBodyType),
                             Hair = entity.persons_signs_hair
                                          .Where(c => c.PersonId == persons.Id)
                                          .Select(h => h.PersonHair)
                         }
                });

    return query.ToList<object>();
}

---

我要试试这个。但是，我几乎可以肯定，如果您使用DefaultIfEmpty，您将为您的结果带来更大的影响。所以，这就是为什么你可能要复制所有东西。忽略这一点，你将拥有我认为你正在寻找的内在连接

var query = from persons in entity.persons where persons.Id == id 
            select new Person
            {
                 PersonName = persons.PersonName,
                 PersonLastName = persons.PersonLastName,
                 PersonPatronymic = persons.PersonPatronymic,
                 SpecialSigns = new PersonSpecialSigns()
                 {
                    BodyType = entity.persons_signs_body_type
                                     .Where(i => i.PersonId == id) 
                                     .Select(i => i.PersonBodyType),
                    Hair = entity.persons_signs_hair
                                 .Where(i => i.PersonId == id)
                                 .Select(i => i.PersonHair)
                 }
            };

另外，作为一项建议，我将首先使用FirstOrDefault检查此人是否存在，然后填充该类

var personData = entity.persons.FirstOrDefault(i = i.Id == id);

if(personData != null)
{
    var person = new Person
    {
        PersonName = personData.PersonName,
        PersonLastName = personData.PersonLastName,
        PersonPatronymic = personData.PersonPatronymic,
        SpecialSigns = new PersonSpecialSigns()
        {
            BodyType = entity.persons_signs_body_type
                             .Where(i => i.PersonId == personData.Id) 
                             .Select(i => i.PersonBodyType),
            Hair = entity.persons_signs_hair
                         .Where(i => i.PersonId == personData.Id)
                         .Select(i => i.PersonHair)
         }
   };
   //continue with the code
}

---

这里的速记linq应该很好用

public List<object> GetPerson(int id)
{
    var query = entity.persons.First(x=> x.Id == id).Select(x=> new Person
                {
                     PersonName = x.PersonName,
                     PersonLastName = x.PersonLastName,
                     PersonPatronymic = x.PersonPatronymic,
                     SpecialSigns = new PersonSpecialSigns                         
                     {
                         BodyType = entity.persons_signs_body_type
                                      .Where(y => y.PersonId == x.Id)
                                      .Select(y => y.PersonBodyType),
                         Hair = entity.persons_signs_hair
                                      .Where(y => y.PersonId == x.Id)
                                      .Select(y => y.PersonHair)
                     }
                 });

    return query.ToList<object>();
}

---

假设您使用的是实体框架，并且您的实体看起来类似于：

Person.cs

public int Id { get; set; }
public string PersonName { get; set; }
public string PersonLastName { get; set; }
public string PersonPatronymic { get; set; }

public ICollection<PersonsSignsHair> PersonsSignsHair { get; set; }
public ICollection<PersonsSignsBodyType> PersonsSignsBodyType { get; set; }

PersonSignsByType.cs

public int Id { get; set; }
public int PersonId { get; set; }
public string PersonBodyType { get; set; }

你有这样的背景：

public DbSet<PersonsSignsHair> PersonsSignsHair { get; set; }
public DbSet<PersonsSignsBodyType> PersonsSignsBodyType { get; set; }
public DbSet<Person> People { get; set; }

---

请把你得到的结果也包括进来。@wdosanjos我想他已经很清楚了：结果重复了6次如果你只需要一条记录，你可以做第一个或默认

public int Id { get; set; }
public int PersonId { get; set; }
public string PersonHair { get; set; }

public int Id { get; set; }
public int PersonId { get; set; }
public string PersonBodyType { get; set; }

public DbSet<PersonsSignsHair> PersonsSignsHair { get; set; }
public DbSet<PersonsSignsBodyType> PersonsSignsBodyType { get; set; }
public DbSet<Person> People { get; set; }

entity.People.Where(x => x.Id == id).Include(y => y.PersonsSignsHair).Include(z => z.PersonsSignsBodyType).FirstOrDefault();