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MSDN Library

Queryable.OrderBy(TSource, TKey) Method (IQueryable(TSource), Expression(Func(TSource, TKey)), IComparer(TKey))

Sorts the elements of a sequence in ascending order by using a specified comparer.

Namespace:  System.Linq
Assemblies:   System.Linq.Queryable (in System.Linq.Queryable.dll)
  System.Core (in System.Core.dll)

static member OrderBy : 
        source:IQueryable<'TSource> * 
        keySelector:Expression<Func<'TSource, 'TKey>> * 
        comparer:IComparer<'TKey> -> IOrderedQueryable<'TSource> 

Type Parameters


The type of the elements of source.


The type of the key returned by the function that is represented by keySelector.


Type: System.Linq.IQueryable(TSource)

A sequence of values to order.

Type: System.Linq.Expressions.Expression(Func(TSource, TKey))

A function to extract a key from an element.

Type: System.Collections.Generic.IComparer(TKey)

An IComparer(T) to compare keys.

Return Value

Type: System.Linq.IOrderedQueryable(TSource)
An IOrderedQueryable(T) whose elements are sorted according to a key.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable(TSource). When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).


source or keySelector or comparer is a null reference (Nothing in Visual Basic).

This method has at least one parameter of type Expression(TDelegate) whose type argument is one of the Func(T, TResult) types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression(TDelegate).

The OrderBy(TSource, TKey)(IQueryable(TSource), Expression(Func(TSource, TKey)), IComparer(TKey)) method generates a MethodCallExpression that represents calling OrderBy(TSource, TKey)(IQueryable(TSource), Expression(Func(TSource, TKey)), IComparer(TKey)) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery(TElement)(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. The result of calling CreateQuery(TElement)(Expression) is cast to type IOrderedQueryable(T) and returned.

The query behavior that occurs as a result of executing an expression tree that represents calling OrderBy(TSource, TKey)(IQueryable(TSource), Expression(Func(TSource, TKey)), IComparer(TKey)) depends on the implementation of the type of the source parameter. The expected behavior is that it sorts the elements of source based on the key obtained by invoking keySelector on each element of source. The comparer parameter is used to compare keys.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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