Query Expression Syntax Examples: Ordering (LINQ to DataSet)
The examples in this topic demonstrate how to use the OrderBy, OrderByDescending, Reverse, and ThenByDescending methods to query a DataSet and order the results using the query expression syntax.
The FillDataSet method used in these examples is specified in Loading Data Into a DataSet.
The examples in this topic use the Contact, Address, Product, SalesOrderHeader, and SalesOrderDetail tables in the AdventureWorks sample database.
The examples in this topic use the following using/Imports statements:
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Globalization;
using System.Linq;
using System.Windows.Forms;
Option Explicit On
Imports System.Linq
Imports System.Linq.Expressions
Imports System.Collections.Generic
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.Common
Imports System.Globalization
For more information, see How to: Create a LINQ to DataSet Project In Visual Studio.
OrderBy
Example
This example uses OrderBy to return a list of contacts ordered by last name.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contacts = ds.Tables["Contact"];
IEnumerable<DataRow> query =
from contact in contacts.AsEnumerable()
orderby contact.Field<string>("LastName")
select contact;
Console.WriteLine("The sorted list of last names:");
foreach (DataRow contact in query)
{
Console.WriteLine(contact.Field<string>("LastName"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim contacts As DataTable = ds.Tables("Contact")
Dim query = _
From contact In contacts.AsEnumerable() _
Select contact _
Order By contact.Field(Of String)("LastName")
Console.WriteLine("The sorted list of last names:")
For Each contact In query
Console.WriteLine(contact.Field(Of String)("LastName"))
Next
Example
This example uses OrderBy to sort a list of contacts by length of last name.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contacts = ds.Tables["Contact"];
IEnumerable<DataRow> query =
from contact in contacts.AsEnumerable()
orderby contact.Field<string>("LastName").Length
select contact;
Console.WriteLine("The sorted list of last names (by length):");
foreach (DataRow contact in query)
{
Console.WriteLine(contact.Field<string>("LastName"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim contacts As DataTable = ds.Tables("Contact")
Dim query = _
From contact In contacts.AsEnumerable() _
Select contact _
Order By contact.Field(Of String)("LastName").Length
Console.WriteLine("The sorted list of last names (by length):")
For Each contact In query
Console.WriteLine(contact.Field(Of String)("LastName"))
Next
OrderByDescending
Example
This example uses orderby… descending (Order By … Descending), which is equivalent to the OrderByDescending method, to sort the price list from highest to lowest.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable products = ds.Tables["Product"];
IEnumerable<Decimal> query =
from product in products.AsEnumerable()
orderby product.Field<Decimal>("ListPrice") descending
select product.Field<Decimal>("ListPrice");
Console.WriteLine("The list price from highest to lowest:");
foreach (Decimal product in query)
{
Console.WriteLine(product);
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim products As DataTable = ds.Tables("Product")
Dim query = _
From product In products.AsEnumerable() _
Select product _
Order By product.Field(Of Decimal)("ListPrice") Descending
Console.WriteLine("The list price From highest to lowest:")
For Each product In query
Console.WriteLine(product.Field(Of Decimal)("ListPrice"))
Next
Reverse
Example
This example uses Reverse to create a list of orders where OrderDate is earlier than Feb 20, 2002.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable orders = ds.Tables["SalesOrderHeader"];
IEnumerable<DataRow> query = (
from order in orders.AsEnumerable()
where order.Field<DateTime>("OrderDate") < new DateTime(2002, 02, 20)
select order).Reverse();
Console.WriteLine("A backwards list of orders where OrderDate < Feb 20, 2002");
foreach (DataRow order in query)
{
Console.WriteLine(order.Field<DateTime>("OrderDate"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim orders As DataTable = ds.Tables("SalesOrderHeader")
Dim query = ( _
From order In orders.AsEnumerable() _
Where order.Field(Of DateTime)("OrderDate") < New DateTime(2002, 2, 20) _
Select order).Reverse()
Console.WriteLine("A backwards list of orders where OrderDate < Feb 20, 2002")
For Each order In query
Console.WriteLine(order.Field(Of DateTime)("OrderDate"))
Next
ThenByDescending
Example
This example uses OrderBy… Descending, which is equivalent to the ThenByDescending method, to sort a list of products, first by name and then by list price, from highest to lowest.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable products = ds.Tables["Product"];
IEnumerable<DataRow> query =
from product in products.AsEnumerable()
orderby product.Field<string>("Name"),
product.Field<Decimal>("ListPrice") descending
select product;
foreach (DataRow product in query)
{
Console.WriteLine("Product ID: {0} Product Name: {1} List Price {2}",
product.Field<int>("ProductID"),
product.Field<string>("Name"),
product.Field<Decimal>("ListPrice"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim products As DataTable = ds.Tables("Product")
Dim query = _
From product In products.AsEnumerable() _
Order By product.Field(Of String)("Name"), _
product.Field(Of Decimal)("ListPrice") Descending _
Select product
For Each product In query
Console.Write("Product ID: " & product.Field(Of Integer)("ProductID"))
Console.Write(" Product Name: " & product.Field(Of String)("Name"))
Console.WriteLine(" List Price: " & product.Field(Of Decimal)("ListPrice"))
Next