如何使用Entity Framework生成此查询以返回相应的集合？

Question

如何使用Entity Framework生成此查询，以返回该问题仅具有一个主题的相应集合。

select * 
from TD_ENCUESTAS as e 
join td_preguntas as p on e.ENC_ID = p.PRE_ENC_ID 
join TC_TEMAS as t on p.PRE_TEM_ID = t.TEM_ID;

Answer 1

鉴于模型已正确设置，这将非常容易：

var encuestas = context.Encuestas
    .Include(x => x.Preguntas.Tema)

为此，您需要：

public class Encuesta
{
    public virtual ICollection<Pregunta> Preguntas { get; set; }
}

public class Pregunta
{
    public Tema Tema { get; set; }
}

public class Tema
{
    // not actually needed but for clarification
    public virtual ICollection<Pregunta> Preguntas { get; set; }
}

Answer 2

using (DBEntities db = new DBEntities())
{
    var user = (from e in db.TD_ENCUESTAS
                join p in db.td_preguntas on e.ENC_ID equals p.PRE_ENC_ID
                join t in db.TC_TEMAS on p.PRE_TEM_ID equals t.TEM_ID;
                select new
                {
                   Name = e.ENC_DESCRIPCION,
                   Address = p.PRE_ACTIVO,
                   .....//So on...//
                });
}