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Queryable.Distinct<TSource> Method (IQueryable<TSource>, IEqualityComparer<TSource>)

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Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Distinct(Of TSource) ( _
    source As IQueryable(Of TSource), _
    comparer As IEqualityComparer(Of TSource) _
) As IQueryable(Of TSource)

public static IQueryable<TSource> Distinct<TSource>(
    this IQueryable<TSource> source,
    IEqualityComparer<TSource> comparer
)

Type Parameters

  • TSource
    The type of the elements of source.

Parameters

Return Value

Type: System.Linq.IQueryable<TSource>
An IQueryable<T> that contains distinct elements from source.

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.

Exceptions

Exception Condition
ArgumentNullException

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

Remarks

The Distinct<TSource>(IQueryable<TSource>, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Distinct<TSource>(IQueryable<TSource>, IEqualityComparer<TSource>) 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 query behavior that occurs as a result of executing an expression tree that represents calling Distinct<TSource>(IQueryable<TSource>, IEqualityComparer<TSource>) depends on the implementation of the type of the source parameter. The expected behavior is that it returns an unordered sequence of the unique items in source by using comparer to compare values.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.