Query SQL to Lambda Expression

Question

I hope you can help me with this.

I want to convert this query from SQL in a lambda expression in C#:

select  
    a.Descripcion 
from 
    pb.MantenimientosTipos a
where 
    a.activo = 1 and
    a.idSegmento in (select b.idSegmento 
                     from pb.MaquinasRelSegm b 
                     where b.idMaquina = 67)

How can I do this?

I have two selectList, "a" and "b", the selectList "a" is list from table b filter by a parameter and the selectList "b" is a list from table a filter by SelectList "a"

private SelectList a (bool agregarTodo = false)
{
    var segmentos = pb.MaquinasRelSegm.Where(x => x.idMaquina == MaquinaId).Select(x => x.Segmentos).ToList();

    if (agregarTodo)
    {
        segmentos.Add(new PB.Domain.Entities.Segmentos { idSegmento = 0, Descripcion = "Todos" });
    }

    return new SelectList(segmentos, "idSegmento", "Descripcion");
}       

private SelectList b (byte idSegmento, bool agregarTodo = false)
{
    var tipos = pb.MantenimientosTipos.Where(x => x.idSegmento == idSegmento && x.Activo).ToList();
    if (agregarTodo)
    {
        tipos.Insert(0, new PB.Domain.Entities.MantenimientosTipos { idTipoMTTO = 0, Descripcion = "Todo" });
    }

    return new SelectList(tipos, "idTipoMTTO", "Descripcion")
}

I want to put only one selectList with this SQL query

This is the relationship in SQL SERVER https://drive.google.com/file/d/0BzpCEYwGGpogRGRaOVNXTDBrTWc/view?usp=sharing

It would help if you would post a diagram of the tables and their relationships. It is hard to write a query if one doesn't know how the data look like. — Matyas
– Matyas, Commented Sep 10, 2015 at 18:30
drive.google.com/file/d/0BzpCEYwGGpogRGRaOVNXTDBrTWc/… this is de ralationship in SQL SERVER — Victor Hernandez
– Victor Hernandez, Commented Sep 10, 2015 at 18:37

Matyas · Accepted Answer · 2015-09-10 18:52:33Z

1

Thanks for the diagram.

try to use this (assuming that pb is the EF context):

var segmentoIds = pb.MaquinasRelSegm
    .Where(a => a.idMaquina == 67)
    .Select(a => a.idSegmento)
    .ToList();

var description = pb.MantenimientosTipos
    .Where(a => a.Activo && segmentoIds.Contains(a.idSegmento))
    .Select(a => a.Description);

answered Sep 10, 2015 at 18:52

Matyas

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3 Comments

Victor Hernandez Over a year ago

thanks for help me, i was thinking to try LINQ but your answer was great

Matyas Over a year ago

That is LINQ, just another syntax.

nivs1978 Over a year ago

You wanted as a query expression instead (the answer above is called a lambda expression)? var segmentoIds = (from a in pb.MaquinasRelSegm where a.idMaquia == 67 select a.idSegmente).ToList();

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