Union(TSource) Method (IQueryable(TSource), IEnumerable(TSource))

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


Produces the set union of two sequences by using the default equality comparer.

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

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


Type: System.Linq.IQueryable<TSource>

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

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

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

Return Value

Type: System.Linq.IQueryable<TSource>

An IQueryable<T> that contains the elements from both input sequences, excluding duplicates.

Type Parameters


The type of the elements of the input sequences.

Exception Condition

source1 or source2 is null.

The Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>) method generates a MethodCallExpression that represents calling Union<TSource>(IQueryable<TSource>, IEnumerable<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>) 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 following code example demonstrates how to use Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>) to obtain the set union of two sequences.

int[] ints1 = { 5, 3, 9, 7, 5, 9, 3, 7 };
int[] ints2 = { 8, 3, 6, 4, 4, 9, 1, 0 };

// Get the set union of the items in the two arrays.
IEnumerable<int> union = ints1.AsQueryable().Union(ints2);

foreach (int num in union)
    Console.Write("{0} ", num);

    This code produces the following output:

    5 3 9 7 8 6 4 1 0

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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