Sorting Data

A sorting operation orders the elements of a sequence based on one or more attributes. The first sort criterion performs a primary sort on the elements. By specifying a second sort criterion, you can sort the elements within each primary sort group.

The following illustration shows the results of an alphabetical sort operation on a sequence of characters.

The standard query operator methods that sort data are listed in the following section.

Methods

Method Name	Description	C# Query Expression Syntax	Visual Basic Query Expression Syntax	More Information
OrderBy	Sorts values in ascending order.	orderby	Order By	Enumerable.OrderBy Queryable.OrderBy
OrderByDescending	Sorts values in descending order.	orderby … descending	Order By … Descending	Enumerable.OrderByDescending Queryable.OrderByDescending
ThenBy	Performs a secondary sort in ascending order.	orderby …, …	Order By …, …	Enumerable.ThenBy Queryable.ThenBy
ThenByDescending	Performs a secondary sort in descending order.	orderby …, … descending	Order By …, … Descending	Enumerable.ThenByDescending Queryable.ThenByDescending
Reverse	Reverses the order of the elements in a collection.	Not applicable.	Not applicable.	Enumerable.Reverse<TSource> Queryable.Reverse<TSource>

Query Expression Syntax Examples

Primary Sort Examples

Primary Ascending Sort

The following example demonstrates how to use the orderby (Order By in Visual Basic) clause in a LINQ query to sort the strings in an array by string length, in ascending order.

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Length _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next 

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output: 

' the 
' fox 
' quick 
' brown 
' jumps

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Length
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    the
    fox
    quick
    brown
    jumps
*/

Primary Descending Sort

The next example demonstrates how to use the orderbydescending (Order By Descending in Visual Basic) clause in a LINQ query to sort the strings by their first letter, in descending order.

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Substring(0, 1) Descending _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next 

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output: 

' the 
' quick 
' jumps 
' fox 
' brown

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Substring(0, 1) descending 
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    the
    quick
    jumps
    fox
    brown
*/

Secondary Sort Examples

Secondary Ascending Sort

The following example demonstrates how to use the orderby (Order By in Visual Basic) clause in a LINQ query to perform a primary and secondary sort of the strings in an array. The strings are sorted primarily by length and secondarily by the first letter of the string, both in ascending order.

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Length, word.Substring(0, 1) _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next 

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output: 

' fox 
' the 
' brown 
' jumps 
' quick

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Length, word.Substring(0, 1)
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    fox
    the
    brown
    jumps
    quick
*/

Secondary Descending Sort

The next example demonstrates how to use the orderbydescending (Order By Descending in Visual Basic) clause in a LINQ query to perform a primary sort, in ascending order, and a secondary sort, in descending order. The strings are sorted primarily by length and secondarily by the first letter of the string.

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Length, word.Substring(0, 1) Descending _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next 

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output: 

' fox 
' the 
' quick 
' jumps 
' brown

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Length, word.Substring(0, 1) descending 
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    the
    fox
    quick
    jumps
    brown
*/

See Also

Tasks

How to: Order the Results of a Join Clause (C# Programming Guide)

How to: Sort a Collection by Using LINQ (Visual Basic)

How to: Sort or Filter Text Data by Any Word or Field (LINQ)

Concepts

Standard Query Operators Overview

Reference

orderby clause (C# Reference)

Order By Clause (Visual Basic)

System.Linq