Query Expression Syntax Examples: Ordering (LINQ to DataSet)

The examples in this topic demonstrate how to use the OrderBy, OrderByDescending, Reverse<TSource>, 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:

Option Explicit On

Imports System
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

using System;
using System.Linq;
using System.Linq.Expressions;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Data.Common;
using 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.
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

// 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"));
}

Example

This example uses OrderBy to sort a list of contacts by length of last name.

' 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

// 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"));
}

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.
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

// 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);
}

Reverse

Example

This example uses Reverse<TSource> to create a list of orders where OrderDate is earlier than Feb 20, 2002.

' 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

// 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"));
}

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.
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

// 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"));
}

See Also

Concepts

Loading Data Into a DataSet

Standard Query Operators Overview

Other Resources

LINQ to DataSet Examples