How to: Page Through Query Results
This topic shows how to page the results of a query. The example gets five Product objects after skipping the first three in the query result, which is sorted by Product.ListPrice. The same example is shown using each of the following Entity Framework query technologies:
LINQ to Entities
Entity SQL with ObjectQuery<T>
Query builder methods of ObjectQuery<T>
The example in this topic is based on the Adventure Works Sales Model. To run the code in this topic, you must have already added the Adventure Works Sales Model to your project and configured your project to use the Entity Framework. For more information, see How to: Use the Entity Data Model Wizard (Entity Framework) or How to: Manually Configure an Entity Framework Project and How to: Manually Define an Entity Data Model (Entity Framework).
Example
This is the LINQ to Entities example.
Using context As New AdventureWorksEntities
'LINQ to Entities only supports Skip on ordered collections.
Dim products As IOrderedQueryable(Of Product) = _
context.Products.OrderBy(Function(p) p.ListPrice)
Dim allButFirst3Products As IQueryable(Of Product) = products.Skip(3)
Console.WriteLine("All but first 3 products:")
For Each product As Product In allButFirst3Products
Console.WriteLine("Name: {0} \t ID: {1}", _
product.Name, _
product.ProductID)
Next
End Using
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
// LINQ to Entities only supports Skip on ordered collections.
IOrderedQueryable<Product> products = context.Products
.OrderBy(p => p.ListPrice);
IQueryable<Product> allButFirst3Products = products.Skip(3);
Console.WriteLine("All but first 3 products:");
foreach (Product product in allButFirst3Products)
{
Console.WriteLine("Name: {0} \t ID: {1}",
product.Name,
product.ProductID);
}
}
This is the Entity SQL example.
Using context As New AdventureWorksEntities()
' Create a query that takes two parameters.
Dim queryString As String = "SELECT VALUE product FROM AdventureWorksEntities.Products AS product " & _
" order by product.ListPrice SKIP @skip LIMIT @limit"
Dim productQuery As New ObjectQuery(Of Product)(queryString, context)
' Add parameters to the collection.
productQuery.Parameters.Add(New ObjectParameter("skip", 3))
productQuery.Parameters.Add(New ObjectParameter("limit", 5))
' Iterate through the collection of Contact items.
For Each result As Product In productQuery
Console.WriteLine("ID: {0}; Name: {1}", result.ProductID, result.Name)
Next
End Using
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
// Create a query that takes two parameters.
string queryString =
@"SELECT VALUE product FROM
AdventureWorksEntities.Products AS product
order by product.ListPrice SKIP @skip LIMIT @limit";
ObjectQuery<Product> productQuery =
new ObjectQuery<Product>(queryString, context);
// Add parameters to the collection.
productQuery.Parameters.Add(new ObjectParameter("skip", 3));
productQuery.Parameters.Add(new ObjectParameter("limit", 5));
// Iterate through the collection of Contact items.
foreach (Product result in productQuery)
Console.WriteLine("ID: {0}; Name: {1}",
result.ProductID, result.Name);
}
This is the query builder method example.
Using context As New AdventureWorksEntities()
' Define the parameters used to define the "page" of returned data.
Dim skipValue As Integer = 3
Dim limitValue As Integer = 5
' Define a query that returns a "page" or the full
' Product data using the Skip and Top methods.
' When Top() follows Skip(), it acts like the LIMIT statement.
Dim query As ObjectQuery(Of Product) = _
context.Products.Skip("it.ListPrice", "@skip", _
New ObjectParameter("skip", skipValue)).Top("@limit", New ObjectParameter("limit", limitValue))
' Iterate through the page of Product items.
For Each result As Product In query
Console.WriteLine("ID: {0}; Name: {1}", result.ProductID, result.Name)
Next
End Using
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
// Define the parameters used to define the "page" of returned data.
int skipValue = 3;
int limitValue = 5;
// Define a query that returns a "page" or the full
// Product data using the Skip and Top methods.
// When Top() follows Skip(), it acts like the LIMIT statement.
ObjectQuery<Product> query = context.Products
.Skip("it.ListPrice", "@skip",
new ObjectParameter("skip", skipValue))
.Top("@limit", new ObjectParameter("limit", limitValue));
// Iterate through the page of Product items.
foreach (Product result in query)
Console.WriteLine("ID: {0}; Name: {1}",
result.ProductID, result.Name);
}