Query Expression Syntax Examples: Partitioning (LINQ to Entities)
The examples in this topic demonstrate how to use the Skip and Take methods to query the AdventureWorks Sales Model using query expression syntax. The AdventureWorks Sales Model used in these examples is built from the Contact, Address, Product, SalesOrderHeader, and SalesOrderDetail tables in the AdventureWorks sample database.
The examples in this topic use the following using/Imports statements:
Option Explicit On
Option Strict On
Imports L2EExamplesVB.AdventureWorksModel
Imports System.Data.Objects
Imports System.Globalization
using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using AdventureWorksModel;
using System.Globalization;
For more information, see How to: Create a LINQ to Entities Project in Visual Studio.
Skip
Example
The following example uses the Skip method to get all but the first two addresses in Seattle.
Using AWEntities As New AdventureWorksEntities
Dim orders As ObjectQuery(Of SalesOrderHeader) = AWEntities.SalesOrderHeader
Dim addresses As ObjectQuery(Of Address) = AWEntities.Address
'LINQ to Entities only supports Skip on ordered collections.
Dim query = ( _
From address In addresses _
From order In orders _
Where address.AddressID = order.Address.AddressID _
And address.City = "Seattle" _
Order By order.SalesOrderID _
Select New With _
{ _
.City = address.City, _
.OrderID = order.SalesOrderID, _
.OrderDate = order.OrderDate _
}).Skip(2)
Console.WriteLine("All but first 2 orders in Seattle:")
For Each order In query
Console.WriteLine("City: {0} Order ID: {1} Total Due: {2:d}", _
order.City, order.OrderID, order.OrderDate)
Next
End Using
using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
ObjectQuery<Address> addresses = AWEntities.Address;
ObjectQuery<SalesOrderHeader> orders = AWEntities.SalesOrderHeader;
//LINQ to Entities only supports Skip on ordered collections.
var query = (
from address in addresses
from order in orders
where address.AddressID == order.Address.AddressID
&& address.City == "Seattle"
orderby order.SalesOrderID
select new
{
City = address.City,
OrderID = order.SalesOrderID,
OrderDate = order.OrderDate
}).Skip(2);
Console.WriteLine("All but first 2 orders in Seattle:");
foreach (var order in query)
{
Console.WriteLine("City: {0} Order ID: {1} Total Due: {2:d}",
order.City, order.OrderID, order.OrderDate);
}
Take
Example
The following example uses the Take method to get the first three addresses in Seattle.
Using AWEntities As New AdventureWorksEntities
Dim orders As ObjectQuery(Of SalesOrderHeader) = AWEntities.SalesOrderHeader
Dim addresses As ObjectQuery(Of Address) = AWEntities.Address
Dim query = ( _
From address In addresses _
From order In orders _
Where address.AddressID = order.Address.AddressID _
And address.City = "Seattle" _
Select New With _
{ _
.City = address.City, _
.OrderID = order.SalesOrderID, _
.OrderDate = order.OrderDate _
}).Take(3)
Console.WriteLine("First 3 orders in Seattle:")
For Each order In query
Console.WriteLine("City: {0} Order ID: {1} Total Due: {2:d}", _
order.City, order.OrderID, order.OrderDate)
Next
End Using
using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
ObjectQuery<Address> addresses = AWEntities.Address;
ObjectQuery<SalesOrderHeader> orders = AWEntities.SalesOrderHeader;
var query = (
from address in addresses
from order in orders
where address.AddressID == order.Address.AddressID
&& address.City == "Seattle"
select new
{
City = address.City,
OrderID = order.SalesOrderID,
OrderDate = order.OrderDate
}).Take(3);
Console.WriteLine("First 3 orders in Seattle:");
foreach (var order in query)
{
Console.WriteLine("City: {0} Order ID: {1} Total Due: {2:d}",
order.City, order.OrderID, order.OrderDate);
}
}