このトピックでは、ナビゲーション プロパティを使用してリレーションシップをナビゲートする方法について説明します。 For more information, see ナビゲーション プロパティ. この例では、姓が "Zhou" である連絡先のすべての注文を取得します。 Contact.SalesOrderHeader ナビゲーション プロパティは、各連絡先の SalesOrderHeader オブジェクトのコレクションを取得するために使用されます。 The same example is shown using each of the following Entity Framework query technologies:
LINQ to Entities
Entity SQL と ObjectQuery<T>
ObjectQuery<T> のクエリ ビルダー メソッド
このトピックの例には、Adventure Works Sales Model が使用されています。このトピックのコードを実行するには、あらかじめプロジェクトに Adventure Works Sales Model を追加し、Entity Framework を使用するようにプロジェクトを構成しておく必要があります。詳細については、「Entity Data Model ウィザードを使用する方法 (Entity Framework)」、または「Entity Framework プロジェクトを手動で構成する方法」、および「Entity Data Model を手動で定義する方法 (Entity Framework)」を参照してください。
例
This is the LINQ to Entities example.
Dim lastName = "Zhou"
Using context As New AdventureWorksEntities
Dim contacts As ObjectSet(Of Contact) = context.Contacts
Dim ordersQuery = From contact In contacts _
Where contact.LastName = lastName _
Select New With _
{.LastName = contact.LastName, _
.Orders = contact.SalesOrderHeaders}
For Each order In ordersQuery
Console.WriteLine("Name: {0}", order.LastName)
For Each orderInfo In order.Orders
Console.WriteLine("Order ID: {0}, Order date: {1}, Total Due: {2}", _
orderInfo.SalesOrderID, orderInfo.OrderDate, orderInfo.TotalDue)
Next
Console.WriteLine("")
Next
End Using
string lastName = "Zhou";
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
ObjectSet<Contact> contacts = context.Contacts;
var ordersQuery = from contact in contacts
where contact.LastName == lastName
select new { LastName = contact.LastName, Orders = contact.SalesOrderHeaders };
foreach (var order in ordersQuery)
{
Console.WriteLine("Name: {0}", order.LastName);
foreach (SalesOrderHeader orderInfo in order.Orders)
{
Console.WriteLine("Order ID: {0}, Order date: {1}, Total Due: {2}",
orderInfo.SalesOrderID, orderInfo.OrderDate, orderInfo.TotalDue);
}
Console.WriteLine("");
}
}
This is the Entity SQL example.
Using context As New AdventureWorksEntities()
Dim esqlQuery As String = "SELECT c.FirstName, c.SalesOrderHeaders " & _
" FROM AdventureWorksEntities.Contacts AS c where c.LastName = @ln"
Dim query As New ObjectQuery(Of DbDataRecord)(esqlQuery, context)
' Add parameters to the collection.
query.Parameters.Add(New ObjectParameter("ln", "Zhou"))
For Each rec As DbDataRecord In query
' Display contact's first name.
Console.WriteLine("First Name {0}: ", rec(0))
Dim list As List(Of SalesOrderHeader) = TryCast(rec(1), List(Of SalesOrderHeader))
' Display SalesOrderHeader information
' associated with the contact.
For Each soh As SalesOrderHeader In list
Console.WriteLine(" Order ID: {0}, Order date: {1}, Total Due: {2}",
soh.SalesOrderID, soh.OrderDate, soh.TotalDue)
Next
Next
End Using
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
string esqlQuery = @"SELECT c.FirstName, c.SalesOrderHeaders
FROM AdventureWorksEntities.Contacts AS c where c.LastName = @ln";
ObjectQuery<DbDataRecord> query = new ObjectQuery<DbDataRecord>(esqlQuery, context);
query.Parameters.Add(new ObjectParameter("ln", "Zhou"));
foreach (DbDataRecord rec in query)
{
// Display contact's first name.
Console.WriteLine("First Name {0}: ", rec[0]);
List<SalesOrderHeader> list = rec[1] as List<SalesOrderHeader>;
// Display SalesOrderHeader information
// associated with the contact.
foreach (SalesOrderHeader soh in list)
{
Console.WriteLine(" Order ID: {0}, Order date: {1}, Total Due: {2}",
soh.SalesOrderID, soh.OrderDate, soh.TotalDue);
}
}
}
これは、クエリ ビルダー メソッドの例です。
Dim lastName = "Zhou"
Using context As New AdventureWorksEntities()
' Define a query that returns a nested
' DbDataRecord for the projection.
Dim query As ObjectQuery(Of DbDataRecord) = context.Contacts.Select("it.FirstName, it.LastName, it.SalesOrderHeaders") _
.Where("it.LastName = @ln", New ObjectParameter("ln", lastName))
For Each rec As DbDataRecord In query.Execute(MergeOption.AppendOnly)
' Display contact's first name.
Console.WriteLine("First Name {0}: ", rec(0))
Dim list As List(Of SalesOrderHeader) = TryCast(rec(2), List(Of SalesOrderHeader))
' Display SalesOrderHeader information
' associated with the contact.
For Each soh As SalesOrderHeader In list
Console.WriteLine(" Order ID: {0}, Order date: {1}, Total Due: {2}", _
soh.SalesOrderID, soh.OrderDate, soh.TotalDue)
Next
Next
End Using
string lastName = "Zhou";
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
// Define a query that returns a nested
// DbDataRecord for the projection.
ObjectQuery<DbDataRecord> query =
context.Contacts.Select("it.FirstName, "
+ "it.LastName, it.SalesOrderHeaders")
.Where("it.LastName = @ln", new ObjectParameter("ln", lastName));
foreach (DbDataRecord rec in
query.Execute(MergeOption.AppendOnly))
{
// Display contact's first name.
Console.WriteLine("First Name {0}: ", rec[0]);
List<SalesOrderHeader> list = rec[2]
as List<SalesOrderHeader>;
// Display SalesOrderHeader information
// associated with the contact.
foreach (SalesOrderHeader soh in list)
{
Console.WriteLine(" Order ID: {0}, " +
"Order date: {1}, Total Due: {2}",
soh.SalesOrderID, soh.OrderDate, soh.TotalDue);
}
}
}
参照
処理手順
方法: クエリ パスを使用して結果を構築する (Entity Framework)
概念
概念モデルに対するクエリ (Entity Framework)
リレーションシップの定義と管理 (Entity Framework)