Enumerable.Join Enumerable.Join Enumerable.Join Enumerable.Join Method

定義

根據相符索引鍵的兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys.

多載

Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>)

根據相符索引鍵的兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys. 預設的相等比較子是用於比較索引鍵。The default equality comparer is used to compare keys.

Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>)

根據相符索引鍵的兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys. 指定IEqualityComparer<T>用來比較索引鍵。A specified IEqualityComparer<T> is used to compare keys.

Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>)

根據相符索引鍵的兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys. 預設的相等比較子是用於比較索引鍵。The default equality comparer is used to compare keys.

public:
generic <typename TOuter, typename TInner, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ Join(System::Collections::Generic::IEnumerable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, Func<TOuter, TKey> ^ outerKeySelector, Func<TInner, TKey> ^ innerKeySelector, Func<TOuter, TInner, TResult> ^ resultSelector);
public static System.Collections.Generic.IEnumerable<TResult> Join<TOuter,TInner,TKey,TResult> (this System.Collections.Generic.IEnumerable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, Func<TOuter,TKey> outerKeySelector, Func<TInner,TKey> innerKeySelector, Func<TOuter,TInner,TResult> resultSelector);
static member Join : seq<'Outer> * seq<'Inner> * Func<'Outer, 'Key> * Func<'Inner, 'Key> * Func<'Outer, 'Inner, 'Result> -> seq<'Result>
<Extension()>
Public Function Join(Of TOuter, TInner, TKey, TResult) (outer As IEnumerable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Func(Of TOuter, TKey), innerKeySelector As Func(Of TInner, TKey), resultSelector As Func(Of TOuter, TInner, TResult)) As IEnumerable(Of TResult)

類型參數

TOuter

第一個序列之項目的類型。The type of the elements of the first sequence.

TInner

第二個序列之項目的類型。The type of the elements of the second sequence.

TKey

索引鍵選取器函式所傳回之索引鍵的類型。The type of the keys returned by the key selector functions.

TResult

結果項目的類型。The type of the result elements.

參數

outer
IEnumerable<TOuter>

要聯結的第一個序列。The first sequence to join.

inner
IEnumerable<TInner>

要加入第一個序列的序列。The sequence to join to the first sequence.

outerKeySelector
Func<TOuter,TKey>

用來從第一個序列各個項目擷取聯結索引鍵的函式。A function to extract the join key from each element of the first sequence.

innerKeySelector
Func<TInner,TKey>

用來從第二個序列各個項目擷取聯結索引鍵的函式。A function to extract the join key from each element of the second sequence.

resultSelector
Func<TOuter,TInner,TResult>

用來從兩個相符項目建立結果項目的函式。A function to create a result element from two matching elements.

傳回

IEnumerable<TResult>

IEnumerable<T>具有類型的項目TResult透過對兩個序列執行內部聯結所取得。An IEnumerable<T> that has elements of type TResult that are obtained by performing an inner join on two sequences.

例外狀況

outer 或是inner或是outerKeySelector或是innerKeySelector或是resultSelectornullouter or inner or outerKeySelector or innerKeySelector or resultSelector is null.

範例

下列程式碼範例示範如何使用Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>)執行一般的索引鍵為基礎的兩個序列的內部聯結。The following code example demonstrates how to use Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>) to perform an inner join of two sequences based on a common key.

class Person
{
    public string Name { get; set; }
}

class Pet
{
    public string Name { get; set; }
    public Person Owner { get; set; }
}

public static void JoinEx1()
{
    Person magnus = new Person { Name = "Hedlund, Magnus" };
    Person terry = new Person { Name = "Adams, Terry" };
    Person charlotte = new Person { Name = "Weiss, Charlotte" };

    Pet barley = new Pet { Name = "Barley", Owner = terry };
    Pet boots = new Pet { Name = "Boots", Owner = terry };
    Pet whiskers = new Pet { Name = "Whiskers", Owner = charlotte };
    Pet daisy = new Pet { Name = "Daisy", Owner = magnus };

    List<Person> people = new List<Person> { magnus, terry, charlotte };
    List<Pet> pets = new List<Pet> { barley, boots, whiskers, daisy };

    // Create a list of Person-Pet pairs where 
    // each element is an anonymous type that contains a
    // Pet's name and the name of the Person that owns the Pet.
    var query =
        people.Join(pets,
                    person => person,
                    pet => pet.Owner,
                    (person, pet) =>
                        new { OwnerName = person.Name, Pet = pet.Name });

    foreach (var obj in query)
    {
        Console.WriteLine(
            "{0} - {1}",
            obj.OwnerName,
            obj.Pet);
    }
}

/*
 This code produces the following output:

 Hedlund, Magnus - Daisy
 Adams, Terry - Barley
 Adams, Terry - Boots
 Weiss, Charlotte - Whiskers
*/
Structure Person
    Public Name As String
End Structure

Structure Pet
    Public Name As String
    Public Owner As Person
End Structure

Sub JoinEx1()
    Dim magnus As New Person With {.Name = "Hedlund, Magnus"}
    Dim terry As New Person With {.Name = "Adams, Terry"}
    Dim charlotte As New Person With {.Name = "Weiss, Charlotte"}

    Dim barley As New Pet With {.Name = "Barley", .Owner = terry}
    Dim boots As New Pet With {.Name = "Boots", .Owner = terry}
    Dim whiskers As New Pet With {.Name = "Whiskers", .Owner = charlotte}
    Dim daisy As New Pet With {.Name = "Daisy", .Owner = magnus}

    Dim people As New List(Of Person)(New Person() {magnus, terry, charlotte})
    Dim pets As New List(Of Pet)(New Pet() {barley, boots, whiskers, daisy})

    ' Create a list of Person-Pet pairs, where each element is an
    ' anonymous type that contains a Pet's name and the name of the 
    ' Person that owns the Pet.
    Dim query =
people.Join(pets,
            Function(person) person,
            Function(pet) pet.Owner,
            Function(person, pet) _
                New With {.OwnerName = person.Name, .Pet = pet.Name})

    Dim output As New System.Text.StringBuilder
    For Each obj In query
        output.AppendLine(obj.OwnerName & " - " & obj.Pet)
    Next

    ' Display the output.
    MsgBox(output.ToString)
End Sub

' This code produces the following output:
'
' Hedlund, Magnus - Daisy
' Adams, Terry - Barley
' Adams, Terry - Boots
' Weiss, Charlotte - Whiskers

備註

實作這個方法是使用延後的執行。This method is implemented by using deferred execution. 立即傳回值是儲存,才能執行此動作的所有資訊的物件。The immediate return value is an object that stores all the information that is required to perform the action. 這個方法所表示的查詢不會執行直到列舉物件可以藉由呼叫其GetEnumerator方法直接或透過foreachVisual C# 中或For EachVisual Basic 中。The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

預設相等比較子, Default,用來雜湊及比較索引鍵。The default equality comparer, Default, is used to hash and compare keys.

聯結是指兩個來源的資訊,根據一般的索引鍵的項目建立相互關聯的作業。A join refers to the operation of correlating the elements of two sources of information based on a common key. Join 將兩個資訊來源和相符的索引鍵用它們會一起其中一種方法呼叫中。Join brings the two information sources and the keys by which they are matched together in one method call. 這不同於使用SelectMany,這需要一個以上的方法呼叫來執行相同的作業。This differs from the use of SelectMany, which requires more than one method call to perform the same operation.

Join 保留的項目順序outer,和每個這些項目,相符項目的順序innerJoin preserves the order of the elements of outer, and for each of these elements, the order of the matching elements of inner.

在查詢運算式語法中, join (Visual C#) 或Join(Visual Basic) 子句會轉譯成的引動過程JoinIn query expression syntax, a join (Visual C#) or Join (Visual Basic) clause translates to an invocation of Join.

在關聯式資料庫規定,Join方法會實作內部等聯結。In relational database terms, the Join method implements an inner equijoin. 「 內部 」 表示只與另一個序列中有符合的項目都包含在結果中。'Inner' means that only elements that have a match in the other sequence are included in the results. 等聯結 ' 是聯結中的索引鍵比較是否相等。An 'equijoin' is a join in which the keys are compared for equality. 左方外部聯結作業有沒有專用的標準查詢運算子,但可以使用來執行GroupJoin方法。A left outer join operation has no dedicated standard query operator, but can be performed by using the GroupJoin method. 請參閱聯結作業See Join Operations.

另請參閱

Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>)

根據相符索引鍵的兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys. 指定IEqualityComparer<T>用來比較索引鍵。A specified IEqualityComparer<T> is used to compare keys.

public:
generic <typename TOuter, typename TInner, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ Join(System::Collections::Generic::IEnumerable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, Func<TOuter, TKey> ^ outerKeySelector, Func<TInner, TKey> ^ innerKeySelector, Func<TOuter, TInner, TResult> ^ resultSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);
public static System.Collections.Generic.IEnumerable<TResult> Join<TOuter,TInner,TKey,TResult> (this System.Collections.Generic.IEnumerable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, Func<TOuter,TKey> outerKeySelector, Func<TInner,TKey> innerKeySelector, Func<TOuter,TInner,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);
static member Join : seq<'Outer> * seq<'Inner> * Func<'Outer, 'Key> * Func<'Inner, 'Key> * Func<'Outer, 'Inner, 'Result> * System.Collections.Generic.IEqualityComparer<'Key> -> seq<'Result>
<Extension()>
Public Function Join(Of TOuter, TInner, TKey, TResult) (outer As IEnumerable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Func(Of TOuter, TKey), innerKeySelector As Func(Of TInner, TKey), resultSelector As Func(Of TOuter, TInner, TResult), comparer As IEqualityComparer(Of TKey)) As IEnumerable(Of TResult)

類型參數

TOuter

第一個序列之項目的類型。The type of the elements of the first sequence.

TInner

第二個序列之項目的類型。The type of the elements of the second sequence.

TKey

索引鍵選取器函式所傳回之索引鍵的類型。The type of the keys returned by the key selector functions.

TResult

結果項目的類型。The type of the result elements.

參數

outer
IEnumerable<TOuter>

要聯結的第一個序列。The first sequence to join.

inner
IEnumerable<TInner>

要加入第一個序列的序列。The sequence to join to the first sequence.

outerKeySelector
Func<TOuter,TKey>

用來從第一個序列各個項目擷取聯結索引鍵的函式。A function to extract the join key from each element of the first sequence.

innerKeySelector
Func<TInner,TKey>

用來從第二個序列各個項目擷取聯結索引鍵的函式。A function to extract the join key from each element of the second sequence.

resultSelector
Func<TOuter,TInner,TResult>

用來從兩個相符項目建立結果項目的函式。A function to create a result element from two matching elements.

comparer
IEqualityComparer<TKey>

IEqualityComparer<T>來雜湊及比較索引鍵。An IEqualityComparer<T> to hash and compare keys.

傳回

IEnumerable<TResult>

IEnumerable<T>具有類型的項目TResult透過對兩個序列執行內部聯結所取得。An IEnumerable<T> that has elements of type TResult that are obtained by performing an inner join on two sequences.

例外狀況

outer 或是inner或是outerKeySelector或是innerKeySelector或是resultSelectornullouter or inner or outerKeySelector or innerKeySelector or resultSelector is null.

備註

實作這個方法是使用延後的執行。This method is implemented by using deferred execution. 立即傳回值是儲存,才能執行此動作的所有資訊的物件。The immediate return value is an object that stores all the information that is required to perform the action. 這個方法所表示的查詢不會執行直到列舉物件可以藉由呼叫其GetEnumerator方法直接或透過foreachVisual C# 中或For EachVisual Basic 中。The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

如果comparernull,預設的相等比較子, Default,用來雜湊及比較索引鍵。If comparer is null, the default equality comparer, Default, is used to hash and compare keys.

聯結是指兩個來源的資訊,根據一般的索引鍵的項目建立相互關聯的作業。A join refers to the operation of correlating the elements of two sources of information based on a common key. Join 將兩個資訊來源和相符的索引鍵用它們會一起其中一種方法呼叫中。Join brings the two information sources and the keys by which they are matched together in one method call. 這不同於使用SelectMany,這需要一個以上的方法呼叫來執行相同的作業。This differs from the use of SelectMany, which requires more than one method call to perform the same operation.

Join 保留的項目順序outer,和每個這些項目,相符項目的順序innerJoin preserves the order of the elements of outer, and for each of these elements, the order of the matching elements of inner.

在關聯式資料庫規定,Join方法會實作內部等聯結。In relational database terms, the Join method implements an inner equijoin. 「 內部 」 表示只與另一個序列中有符合的項目都包含在結果中。'Inner' means that only elements that have a match in the other sequence are included in the results. 等聯結 ' 是聯結中的索引鍵比較是否相等。An 'equijoin' is a join in which the keys are compared for equality. 左方外部聯結作業有沒有專用的標準查詢運算子,但可以使用來執行GroupJoin方法。A left outer join operation has no dedicated standard query operator, but can be performed by using the GroupJoin method. 請參閱聯結作業See Join Operations.

另請參閱

適用於