방법: 쿼리 경로를 사용하여 결과 모양 결정(Entity Framework)
이 항목에서는 EDM(엔터티 데이터 모델)의 특정 개체를 쿼리할 때 반환되는 관련 개체를 정의하는 쿼리 경로를 지정하는 방법에 대한 예제를 제공합니다. 이 예제의 쿼리에서는 단일 Contact 개체 및 관련된 SalesOrderHeader 및 SalesOrderDetail 개체를 모두 반환합니다. 다음의 엔터티 프레임워크 쿼리 기술을 각각 사용하여 동일한 예제를 보여 줍니다.
LINQ to Entities
ObjectQuery<T>를 사용한 Entity SQL
ObjectQuery<T>의 쿼리 작성기 메서드
이 항목의 예제는 Adventure Works Sales 모델을 기반으로 합니다. 이 예제의 코드를 실행하려면 프로젝트에 AdventureWorks Sales 모델을 추가하고 Entity Framework를 사용하도록 프로젝트를 구성해야 합니다. 이렇게 하려면 방법: Entity Framework 프로젝트 수동 구성 및 방법: 엔터티 데이터 모델 수동 정의(Entity Framework)의 절차를 수행합니다. 엔터티 데이터 모델 마법사를 사용하여 AdventureWorks Sales 모델을 정의할 수도 있습니다. 자세한 내용은 방법: 엔터티 데이터 모델 마법사 사용(Entity Framework)을 참조하십시오.
예제
다음은 LINQ to Entities 예제입니다.
Using context As New AdventureWorksEntities
' Define a LINQ query with a path that returns
' orders and items for a contact.
Dim contacts = (From contact In context.Contact _
.Include("SalesOrderHeader.SalesOrderDetail") _
Select contact).FirstOrDefault()
Try
' Execute the query and display information for each item
' in the orders that belong to the contact.
For Each order As SalesOrderHeader In contacts.SalesOrderHeader
Console.WriteLine(String.Format("PO Number: {0}", _
order.PurchaseOrderNumber))
Console.WriteLine(String.Format("Order Date: {0}", _
order.OrderDate.ToString()))
Console.WriteLine("Order items:")
For Each item As SalesOrderDetail In order.SalesOrderDetail
Console.WriteLine(String.Format("Product:{0}" _
+ "Quantity: {1}", item.ProductID.ToString(), _
item.OrderQty.ToString()))
Next
Next
Catch ex As EntitySqlException
Console.WriteLine(ex.ToString())
Catch ex As EntityCommandExecutionException
Console.WriteLine(ex.ToString())
End Try
End Using
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
// Define a LINQ query with a path that returns
// orders and items for a contact.
var contacts = (from contact in context.Contact
.Include("SalesOrderHeader.SalesOrderDetail")
select contact).FirstOrDefault();
try
{
// Execute the query and display information for each item
// in the orders that belong to the contact.
foreach (SalesOrderHeader order in contacts
.SalesOrderHeader)
{
Console.WriteLine(String.Format("PO Number: {0}",
order.PurchaseOrderNumber));
Console.WriteLine(String.Format("Order Date: {0}",
order.OrderDate.ToString()));
Console.WriteLine("Order items:");
foreach (SalesOrderDetail item in order.SalesOrderDetail)
{
Console.WriteLine(String.Format("Product: {0} "
+ "Quantity: {1}", item.ProductID.ToString(),
item.OrderQty.ToString()));
}
}
}
catch (EntitySqlException ex)
{
Console.WriteLine(ex.ToString());
}
catch (EntityCommandExecutionException ex)
{
Console.WriteLine(ex.ToString());
}
}
다음은 Entity SQL 예제입니다.
Using context As New AdventureWorksEntities
' Define an object query with a path that returns
' orders and items for a specific contact.
Dim queryString As String = _
"SELECT VALUE TOP(1) Contact FROM " + _
"AdventureWorksEntities.Contact AS Contact"
' Define the object query with the query string.
Dim contactQuery As New ObjectQuery(Of Contact)(queryString, _
context, MergeOption.NoTracking)
Dim contact As Contact = _
contactQuery.Include("SalesOrderHeader.SalesOrderDetail") _
.FirstOrDefault()
Try
' Execute the query and display information for each item
' in the orders that belong to the first contact.
For Each order As SalesOrderHeader In contact.SalesOrderHeader
Console.WriteLine(String.Format("PO Number: {0}", _
order.PurchaseOrderNumber))
Console.WriteLine(String.Format("Order Date: {0}", _
order.OrderDate.ToString()))
Console.WriteLine("Order items:")
For Each item As SalesOrderDetail In order.SalesOrderDetail
Console.WriteLine(String.Format("Product:{0}" _
+ "Quantity: {1}", item.ProductID.ToString(), _
item.OrderQty.ToString()))
Next
Next
Catch ex As EntitySqlException
Console.WriteLine(ex.ToString())
Catch ex As EntityCommandExecutionException
Console.WriteLine(ex.ToString())
End Try
End Using
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
// Define an object query with a path that returns
// orders and items for a specific contact.
string queryString =
@"SELECT VALUE TOP(1) Contact FROM " +
"AdventureWorksEntities.Contact AS Contact";
// Define the object query with the query string.
ObjectQuery<Contact> contactQuery = new ObjectQuery<Contact>(queryString,
context, MergeOption.NoTracking);
Contact contact =
contactQuery.Include("SalesOrderHeader.SalesOrderDetail")
.FirstOrDefault();
try
{
// Execute the query and display information for each item
// in the orders that belong to the first contact.
foreach (SalesOrderHeader order in contact
.SalesOrderHeader)
{
Console.WriteLine(String.Format("PO Number: {0}",
order.PurchaseOrderNumber));
Console.WriteLine(String.Format("Order Date: {0}",
order.OrderDate.ToString()));
Console.WriteLine("Order items:");
foreach (SalesOrderDetail item in order.SalesOrderDetail)
{
Console.WriteLine(String.Format("Product: {0} "
+ "Quantity: {1}", item.ProductID.ToString(),
item.OrderQty.ToString()));
}
}
}
catch (EntitySqlException ex)
{
Console.WriteLine(ex.ToString());
}
catch (EntityCommandExecutionException ex)
{
Console.WriteLine(ex.ToString());
}
}
다음은 쿼리 작성기 방법을 사용한 예제입니다.
Using context As New AdventureWorksEntities
' Create an object query with a path that returns orders and items for a contact.
Dim contact As Contact = _
context.Contact.Include("SalesOrderHeader.SalesOrderDetail") _
.FirstOrDefault()
Try
' Execute the query and display information for each item
' in the orders that belong to the returned contact.
Dim order As SalesOrderHeader
For Each order In contact.SalesOrderHeader
Console.WriteLine(String.Format("PO Number: {0}", _
order.PurchaseOrderNumber))
Console.WriteLine(String.Format("Order Date: {0}", _
order.OrderDate.ToString()))
Console.WriteLine("Order items:")
Dim item As SalesOrderDetail
For Each item In order.SalesOrderDetail
Console.WriteLine(String.Format("Product:{0}" _
+ "Quantity: {1}", item.ProductID.ToString(), _
item.OrderQty.ToString()))
Next
Next
Catch ex As EntitySqlException
Console.WriteLine(ex.ToString())
Catch ex As EntityCommandExecutionException
Console.WriteLine(ex.ToString())
End Try
End Using
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
// Define an object query with a path that returns
// orders and items for a specific contact.
Contact contact =
context.Contact.Include("SalesOrderHeader.SalesOrderDetail")
.FirstOrDefault();
try
{
// Execute the query and display information for each item
// in the orders that belong to the first contact.
foreach (SalesOrderHeader order in contact
.SalesOrderHeader)
{
Console.WriteLine(String.Format("PO Number: {0}",
order.PurchaseOrderNumber));
Console.WriteLine(String.Format("Order Date: {0}",
order.OrderDate.ToString()));
Console.WriteLine("Order items:");
foreach (SalesOrderDetail item in order.SalesOrderDetail)
{
Console.WriteLine(String.Format("Product: {0} "
+ "Quantity: {1}", item.ProductID.ToString(),
item.OrderQty.ToString()));
}
}
}
catch (EntitySqlException ex)
{
Console.WriteLine(ex.ToString());
}
catch (EntityCommandExecutionException ex)
{
Console.WriteLine(ex.ToString());
}
}
참고 항목
작업
방법: 엔터티 형식을 반환하는 쿼리 실행(Entity Framework)
방법: 탐색 속성을 사용하여 관계 탐색(Entity Framework)
개념
쿼리 결과 셰이핑(Entity Framework)
쿼리 작성기 메서드(Entity Framework)
Entity SQL 개요