Queryable.Union Method

Definition

Namespace:

System.Linq

Assembly:

System.Linq.Queryable.dll

Produces the set union of two sequences.

Overloads

Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>)	Produces the set union of two sequences by using the default equality comparer.
Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set union of two sequences by using a specified IEqualityComparer<T>.

Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>)

Source:

Queryable.cs

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

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Union(System::Linq::IQueryable<TSource> ^ source1, System::Collections::Generic::IEnumerable<TSource> ^ source2);

public static System.Linq.IQueryable<TSource> Union<TSource> (this System.Linq.IQueryable<TSource> source1, System.Collections.Generic.IEnumerable<TSource> source2);

static member Union : System.Linq.IQueryable<'Source> * seq<'Source> -> System.Linq.IQueryable<'Source>

<Extension()>
Public Function Union(Of TSource) (source1 As IQueryable(Of TSource), source2 As IEnumerable(Of TSource)) As IQueryable(Of TSource)

Type Parameters

TSource

The type of the elements of the input sequences.

Parameters

source1

IQueryable<TSource>

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

source2

IEnumerable<TSource>

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

Returns

IQueryable<TSource>

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

Exceptions

ArgumentNullException

source1 or source2 is null.

Examples

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
*/

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.
MsgBox(output.ToString())

' This code produces the following output:

' 5 3 9 7 8 6 4 1 0

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.

Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Source:

Queryable.cs

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

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Union(System::Linq::IQueryable<TSource> ^ source1, System::Collections::Generic::IEnumerable<TSource> ^ source2, System::Collections::Generic::IEqualityComparer<TSource> ^ comparer);

public static System.Linq.IQueryable<TSource> Union<TSource> (this System.Linq.IQueryable<TSource> source1, System.Collections.Generic.IEnumerable<TSource> source2, System.Collections.Generic.IEqualityComparer<TSource>? comparer);

static member Union : System.Linq.IQueryable<'Source> * seq<'Source> * System.Collections.Generic.IEqualityComparer<'Source> -> System.Linq.IQueryable<'Source>

<Extension()>
Public Function Union(Of TSource) (source1 As IQueryable(Of TSource), source2 As IEnumerable(Of TSource), comparer As IEqualityComparer(Of TSource)) As IQueryable(Of TSource)

Type Parameters

TSource

The type of the elements of the input sequences.

Parameters

source1

IQueryable<TSource>

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

source2

IEnumerable<TSource>

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

comparer

IEqualityComparer<TSource>

An IEqualityComparer<T> to compare values.

Returns

IQueryable<TSource>

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

Exceptions

ArgumentNullException

source1 or source2 is null.

Remarks

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.