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

Produces the set union of two sequences by using a specified IEqualityComparer<T>.

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

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

Type Parameters

TSource

The type of the elements of the input sequences.

Parameters

source1
Type: System.Linq.IQueryable<TSource>

A sequence whose distinct elements form the first set for the union operation.

source2
Type: System.Collections.Generic.IEnumerable<TSource>

A sequence whose distinct elements form the second set for the union operation.

comparer
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 elements from both input sequences, excluding duplicates.

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).

ExceptionCondition
ArgumentNullException

source1 or source2 is null.

The Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Union<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 the source1 parameter.

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

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5

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