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

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

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

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Union(Of TSource) ( _
    source1 As IQueryable(Of TSource), _
    source2 As IEnumerable(Of TSource) _
) As IQueryable(Of TSource)

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

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.

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.

Exceptions

Exception Condition
ArgumentNullException

source1 or source2 is nulla null reference (Nothing in Visual Basic).

Remarks

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.

Examples

The following code example demonstrates how to use Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>) to obtain the set union of two sequences.

      Dim ints1() As Integer = {5, 3, 9, 7, 5, 9, 3, 7}
      Dim ints2() As Integer = {8, 3, 6, 4, 4, 9, 1, 0}

      ' Get the set union of the items in the two arrays.
      Dim union = ints1.AsQueryable().Union(ints2)

      Dim output As New System.Text.StringBuilder
      For Each num As Integer In union
         output.Append(String.Format("{0} ", num))
      Next

      ' Display the output.
      outputBlock.Text &= output.ToString() & vbCrLf

      ' This code produces the following output:

      ' 5 3 9 7 8 6 4 1 0


         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)
            outputBlock.Text += String.Format("{0} ", num);

         /*
             This code produces the following output:

             5 3 9 7 8 6 4 1 0
         */

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.