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How to: Navigate Relationships with the Navigate Operator

This topic shows how to execute a command against a conceptual model by using an EntityCommand object, and how to retrieve the RefType results by using an EntityDataReader.

To run the code in this example

  1. Add the AdventureWorks Sales Model to your project and configure your project to use the Entity Framework. For more information, see How to: Use the Entity Data Model Wizard (Entity Framework).

  2. In the code page for your application, add the following using statements (Imports in Visual Basic):

    
    using System;
    using System.Collections.Generic;
    using System.Collections;
    using System.Data.Common;
    using System.Data;
    using System.IO;
    using System.Data.SqlClient;
    using System.Data.EntityClient;
    using System.Data.Metadata.Edm;
        
    

Example

The following example shows how to navigate relationships in Entity SQL by using the NAVIGATE operator. The Navigate operator takes the following parameters: an instance of an entity, the relationship type, the end of the relationship, and the beginning of the relationship. Optionally, you can pass only an instance of an entity and the relationship type to the Navigate operator.


using (EntityConnection conn =
new EntityConnection("name=AdventureWorksEntities"))
{
conn.Open();
// Create an EntityCommand.
using (EntityCommand cmd = conn.CreateCommand())
{
// Create an Entity SQL query.
string esqlQuery =
@"SELECT address.AddressID, (SELECT VALUE DEREF(soh) FROM
NAVIGATE(address, AdventureWorksModel.FK_SalesOrderHeader_Address_BillToAddressID)
AS soh) FROM AdventureWorksEntities.Addresses AS address";


cmd.CommandText = esqlQuery;

// Execute the command.
using (DbDataReader rdr = cmd.ExecuteReader(CommandBehavior.SequentialAccess))
{
// Start reading.
while (rdr.Read())
{
Console.WriteLine(rdr["AddressID"]);
}
}
}
conn.Close();
}
    

See Also




Build Date:

2012-08-02
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