C# LinQ to Entities：用四个表JOIN查询

LinQ to Entities: Query with four tables JOIN

提问by VansFannel

I have four tables:

我有四个表：

- Client with PK ClientID.
- Destination with PK DestinationID.
- Language with PK LanguageID.
- DestinationDetail with PK DestinationID.
- RL-Client-Destination with PKs ClientID and DestinationID.

The Client may have zero or n Destinations. A destination has n DestinationDetails, each of these DestinationDetail has a language.

客户端可能有零个或 n 个目的地。一个目的地有 n 个 DestinationDetails，每个 DestinationDetail 都有一种语言。

Ok. I need to retrieve all of DestinationDetails for a given client and a given language.

好的。我需要检索给定客户端和给定语言的所有 DestinationDetails。

I start writing this:

我开始写这个：

try
   {
      ObjectQuery clientes = 
          guiaContext.Cliente;
      ObjectQuery destinos =
          guiaContext.Destino;
      ObjectQuery idiomas =
          guiaContext.Idioma;
      ObjectQuery detalles =
          guiaContext.DetalleDestino;

      IQueryable detalleQuery =
          from cliente in clientes
          from destino in destinos
          from idioma in idiomas
          from detalleDestino in detalles
          where destino.
          select detalleDestino;

   }
   catch
   {
   }
}

Any advice?

有什么建议吗？

Thanks!

谢谢！

采纳答案by eglasius

Its along the lines:

它的思路是：

var detalleQuery =
          from client in guiaContext.Clients
          where client.ID == 1
          from destination in cliente.Destinations
          from destinationDetail in destination.DestionationDetails
          where destinationDetail.Language.Iso2Code == "es"
          select destinationDetail;

回答by Jonathan Parker

Have you tried doing linq joins:

你有没有试过做 linq 连接：

Select from multiple table using LINQ

使用 LINQ 从多个表中选择

回答by VansFannel

My answer:

我的答案：

var db = new PracticeEntities();
            var destinations = db.DestinationDetails.
                Where(dd => dd.Language.Lang == "en-US" &&
                dd.Destination.Client.Any(c => c.Email == "[email protected]"));

Thanks!

谢谢！