Queryable.Except<TSource> Method (IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.

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

public static IQueryable<TSource> Except<TSource>(
	this IQueryable<TSource> source1,
	IEnumerable<TSource> source2,
	IEqualityComparer<TSource> comparer

Type Parameters


The type of the elements of the input sequences.


Type: System.Linq.IQueryable<TSource>
An IQueryable<T> whose elements that are not also in source2 will be returned.
Type: System.Collections.Generic.IEnumerable<TSource>
An IEnumerable<T> whose elements that also occur in the first sequence will not appear in the returned sequence.
Type: System.Collections.Generic.IEqualityComparer<TSource>
An IEqualityComparer<T> to compare values.

Return Value

Type: System.Linq.IQueryable<TSource>
An IQueryable<T> that contains the set difference of the two sequences.

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.


source1 or source2 is null.

The Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Except<TSource>(IQueryable<TSource>, IEnumerable<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 thesource1 parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) depends on the implementation of the type of the source1 parameter. The expected behavior is that all the elements in source1 are returned except for those that are also in source2, and comparer is used to compare values.


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

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

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