How to join with more than two lists?

Question

How to join with more than two lists?

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#1 by (4 votes)

3

I have three classes:

class Cbo
{
    public string ProfId { get; set; }
    public string Cbo { get; set; }
    public string Descricao { get; set; }
}

class Profissional
{
    public string ProfId { get; set; }
    public string NomeProf { get; set; }
}

class Vinculo
{
    public string UnidadeId { get; set; }
    public string ProfId { get; set; }
    public string Cbo { get; set; }
    public string NomeProf { get; set; }
    public string Descricao { get; set; }
}

I need to create a list using LINQ:

select * from Cbo, Profissional, Vinculo where
Cbo.ProfId = Profissional.ProfId and
Vinculo.ProfId = Profissional.ProfId

I can do with two tables like this:

List<Vinculo> result = (from vinculo in listaVinculo join profissional in listaProfissional on vinculo.ProfId equals profissional.ProfId
select new Vinculo()
{
Cbo = vinculo.Cbo,
NomeProf = profissional.NomeProf,
ProfId = profissional.ProfId,
UnidadeId = vinculo.UnidadeId
}).ToList();

With this code I bind the Profissional and Vinculo classes, but I still do not know how to include the Cbo class to get the descricao field.

c# linq

asked by anonymous 29.01.2017 / 19:26

1 answer

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score 4 · Accepted Answer

Linq has the command join that allows tables or lists to be joined according to an established criterion, in this case the criteria used are the IDs of their lists Cbo , Profissional and Vinculo .

I used ProfId of relation, but others can be used.

See this example:

var joinRes = (
                from Item1 in profs
                join Item2 in cbos on Item1.ProfId equals Item2.ProfId
                join Item3 in vins on Item2.ProfId equals Item3.ProfId
                select new
                {
                    Item1,
                    Item2,
                    Item3
                }
              ).ToList();

joinRes.ForEach(x => 
{
    Console.WriteLine(x.Item1.NomeProf);
    Console.WriteLine(x.Item2.Descricao);
    Console.WriteLine(x.Item3.Descricao);
});

Output

Cat
  Here is the description of Cbo
  Cat Unit

Follow the complete code:

using System;
using System.Collections.Generic;
using System.Linq;

namespace JoinExemploLinq
{
    class Cbo
    {
        public string ProfId { get; set; }
        public string CboId { get; set; }
        public string Descricao { get; set; }
    }

    class Profissional
    {
        public string ProfId { get; set; }
        public string NomeProf { get; set; }
    }

    class Vinculo
    {
        public string UnidadeId { get; set; }
        public string ProfId { get; set; }
        public string CboID { get; set; }
        public string NomeProf { get; set; }
        public string Descricao { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            List<Cbo> cbos = new List<Cbo>
            {
                new Cbo
                {
                    ProfId = "1",
                    CboId = "1",
                    Descricao = "Aqui e a descricao do Cbo"
                }
            };

            List<Profissional> profs = new List<Profissional>
            {
                new Profissional
                {
                    ProfId = "1",
                    NomeProf = "Gato"
                }
            };

            List<Vinculo> vins = new List<Vinculo>
            {
                new Vinculo
                {
                    UnidadeId = "1",
                    ProfId = "1",
                    CboID = "1",
                    NomeProf = "Gato",
                    Descricao = "Unidade do gato"
                }
            };

            var joinRes = (
                            from Item1 in profs
                            join Item2 in cbos on Item1.ProfId equals Item2.ProfId
                            join Item3 in vins on Item2.ProfId equals Item3.ProfId
                            select new
                            {
                                Item1,
                                Item2,
                                Item3
                            }
                          ).ToList();

            joinRes.ForEach(x => 
            {
                Console.WriteLine(x.Item1.NomeProf);
                Console.WriteLine(x.Item2.Descricao);
                Console.WriteLine(x.Item3.Descricao);
            });

            Console.ReadKey();
        }
    }
}

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