HOW TO：執行可傳回複雜型別的查詢 (EntityClient)

本主題顯示如何執行會傳回內含複雜型別屬性之實體類型物件的 Entity SQL 查詢。

執行這個範例中的程式碼

1. 將 AdventureWorks 銷售模型 加入至專案中，並將專案設定為使用 Entity Framework 。 如需詳細資訊，請參閱 HOW TO：使用實體資料模型精靈 (Entity Framework)。

2. 在應用程式的字碼頁中加入下列 using 陳述式 (在 Visual Basic 中為 Imports)：

   Imports System
   Imports System.Collections.Generic
   Imports System.Collections
   Imports System.Data.Common
   Imports System.Data
   Imports System.IO
   Imports System.Data.SqlClient
   Imports System.Data.EntityClient
   Imports System.Data.Metadata.Edm
   

   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;
   

3. 您可以在實體設計工具的 [模型瀏覽器] 視窗中按兩下 .edmx 檔顯示模型。 在實體設計工具介面上，選取 Contact 實體類型的 Email 和 Phone 屬性，然後以滑鼠右鍵按一下並選取 [重構至新的複雜型別]。

4. 含有已選取之 Email 和 Phone 屬性的新複雜型別隨即會加入到 [模型瀏覽器]。 複雜型別已有預設名稱：請在 [屬性] 視窗中將型別重新命名為 EmailPhone。 也會將新的 ComplexProperty 屬性加入至 Contact 實體類型。 將屬性重新命名為 EmailPhoneComplexType.

   如需使用實體資料模型精靈來建立及修改複雜型別的詳細資訊，請參閱 How to: Refactor Existing Properties into a Complex Type Property (Entity Data Model Tools) 和 How to: Create and Modify Complex Types。

範例

下列範例所執行的查詢，會傳回 Contact 物件的集合並顯示 Contact 物件的兩個屬性：ContactID 和 EmailPhoneComplexType 複雜型別的值。

Using conn As New EntityConnection("name=AdventureWorksEntities")
    conn.Open()

    Dim esqlQuery As String = "SELECT VALUE contacts FROM" & _
        " AdventureWorksEntities.Contacts AS contacts WHERE contacts.ContactID == @id"

    ' Create an EntityCommand. 
    Using cmd As EntityCommand = conn.CreateCommand()
        cmd.CommandText = esqlQuery
        Dim param As New EntityParameter()
        param.ParameterName = "id"
        param.Value = 3
        cmd.Parameters.Add(param)
        ' Execute the command. 
        Using rdr As EntityDataReader = cmd.ExecuteReader(CommandBehavior.SequentialAccess)
            ' The result returned by this query contains 
            ' Address complex Types. 
            While rdr.Read()
                ' Display CustomerID 
                Console.WriteLine("Contact ID: {0}", rdr("ContactID"))
                ' Display Address information. 
                Dim nestedRecord As DbDataRecord = TryCast(rdr("EmailPhoneComplexProperty"), DbDataRecord)
                Console.WriteLine("Email and Phone Info:")
                For i As Integer = 0 To nestedRecord.FieldCount - 1
                    Console.WriteLine((" " & nestedRecord.GetName(i) & ": ") + nestedRecord.GetValue(i))
                Next
            End While
        End Using
    End Using
    conn.Close()
End Using

using (EntityConnection conn =
    new EntityConnection("name=AdventureWorksEntities"))
{
    conn.Open();

    string esqlQuery = @"SELECT VALUE contacts FROM
            AdventureWorksEntities.Contacts AS contacts 
            WHERE contacts.ContactID == @id";

    // Create an EntityCommand.
    using (EntityCommand cmd = conn.CreateCommand())
    {
        cmd.CommandText = esqlQuery;
        EntityParameter param = new EntityParameter();
        param.ParameterName = "id";
        param.Value = 3;
        cmd.Parameters.Add(param);

        // Execute the command.
        using (EntityDataReader rdr =
            cmd.ExecuteReader(CommandBehavior.SequentialAccess))
        {
            // The result returned by this query contains 
            // Address complex Types.
            while (rdr.Read())
            {
                // Display CustomerID
                Console.WriteLine("Contact ID: {0}",
                    rdr["ContactID"]);
                // Display Address information.
                DbDataRecord nestedRecord =
                    rdr["EmailPhoneComplexProperty"] as DbDataRecord;
                Console.WriteLine("Email and Phone Info:");
                for (int i = 0; i < nestedRecord.FieldCount; i++)
                {
                    Console.WriteLine("  " + nestedRecord.GetName(i) +
                        ": " + nestedRecord.GetValue(i));
                }
            }
        }
    }
    conn.Close();
}