Queryable.Join Queryable.Join Queryable.Join Queryable.Join Method

定義

根據相符索引鍵,將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>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>)

根據相符索引鍵,將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>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>)

根據相符索引鍵,將兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys. 指定的 IEqualityComparer<T> 是用於比較索引鍵。A specified IEqualityComparer<T> is used to compare keys.

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

根據相符索引鍵,將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::Linq::IQueryable<TResult> ^ Join(System::Linq::IQueryable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, System::Linq::Expressions::Expression<Func<TOuter, TKey> ^> ^ outerKeySelector, System::Linq::Expressions::Expression<Func<TInner, TKey> ^> ^ innerKeySelector, System::Linq::Expressions::Expression<Func<TOuter, TInner, TResult> ^> ^ resultSelector);
public static System.Linq.IQueryable<TResult> Join<TOuter,TInner,TKey,TResult> (this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<Func<TOuter,TKey>> outerKeySelector, System.Linq.Expressions.Expression<Func<TInner,TKey>> innerKeySelector, System.Linq.Expressions.Expression<Func<TOuter,TInner,TResult>> resultSelector);
static member Join : System.Linq.IQueryable<'Outer> * seq<'Inner> * System.Linq.Expressions.Expression<Func<'Outer, 'Key>> * System.Linq.Expressions.Expression<Func<'Inner, 'Key>> * System.Linq.Expressions.Expression<Func<'Outer, 'Inner, 'Result>> -> System.Linq.IQueryable<'Result>
<Extension()>
Public Function Join(Of TOuter, TInner, TKey, TResult) (outer As IQueryable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Expression(Of Func(Of TOuter, TKey)), innerKeySelector As Expression(Of Func(Of TInner, TKey)), resultSelector As Expression(Of Func(Of TOuter, TInner, TResult))) As IQueryable(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
IQueryable<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
Expression<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
Expression<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
Expression<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

IQueryable<TResult>

IQueryable<T>,其具有透過對兩個序列執行內部聯結所取得之型別 TResult 的項目。An IQueryable<T> that has elements of type TResult obtained by performing an inner join on two sequences.

例外狀況

outerinnerouterKeySelectorinnerKeySelectorresultSelectornullouter 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>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) , 根據一般索引鍵來執行兩個序列的內部聯結。The following code example demonstrates how to use Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<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 };

    // Join the list of Person objects and the list of Pet objects 
    // to create a list of person-pet pairs where each element is 
    // an anonymous type that contains the name of pet and the name
    // of the person that owns the pet.
    var query = people.AsQueryable().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

Shared 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})

    ' Join the list of Person objects and the list of Pet objects 
    ' to create a list of person-pet pairs where each element is 
    ' an anonymous type that contains pet's name and the name of the
    ' Person object that owns the pet.
    Dim query = people.AsQueryable().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(String.Format( _
            "{0} - {1}", 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

這個方法至少有一個類型Expression<TDelegate>的參數, 其類型引數是其中一個Func<T,TResult>類型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 針對這些參數, 您可以傳入 lambda 運算式, 它會編譯成Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

方法會產生, 其代表以Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>)結構化泛型方法的方式呼叫本身。 MethodCallExpression Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>)The Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) method generates a MethodCallExpression that represents calling Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) itself as a constructed generic method. 然後, 它會MethodCallExpression將傳遞CreateQuery<TElement>(Expression)至由Provider outer參數IQueryProvider的屬性所表示之的方法。It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the outer parameter.

因執行代表呼叫Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>)之運算式樹狀架構而產生的查詢行為, 取決於outer參數類型的實作為。The query behavior that occurs as a result of executing an expression tree that represents calling Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) depends on the implementation of the type of the outer parameter. 預期的行為是內部聯結的行為。The expected behavior is that of an inner join. 和函式是用來分別從outerinner提取金鑰。 innerKeySelector outerKeySelectorThe outerKeySelector and innerKeySelector functions are used to extract keys from outer and inner, respectively. 這些按鍵會比較是否相等, 以符合每個序列中的元素。These keys are compared for equality to match elements from each sequence. 會為中inner的每個元素儲存一組專案, 以符合中outer的專案。A pair of elements is stored for each element in inner that matches an element in outer. resultSelector然後叫用函式, 從每一對相符的元素投影結果物件。Then the resultSelector function is invoked to project a result object from each pair of matching elements.

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

根據相符索引鍵,將兩個序列的項目相互關聯。Correlates the elements of two sequences based on matching keys. 指定的 IEqualityComparer<T> 是用於比較索引鍵。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::Linq::IQueryable<TResult> ^ Join(System::Linq::IQueryable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, System::Linq::Expressions::Expression<Func<TOuter, TKey> ^> ^ outerKeySelector, System::Linq::Expressions::Expression<Func<TInner, TKey> ^> ^ innerKeySelector, System::Linq::Expressions::Expression<Func<TOuter, TInner, TResult> ^> ^ resultSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);
public static System.Linq.IQueryable<TResult> Join<TOuter,TInner,TKey,TResult> (this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<Func<TOuter,TKey>> outerKeySelector, System.Linq.Expressions.Expression<Func<TInner,TKey>> innerKeySelector, System.Linq.Expressions.Expression<Func<TOuter,TInner,TResult>> resultSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);
static member Join : System.Linq.IQueryable<'Outer> * seq<'Inner> * System.Linq.Expressions.Expression<Func<'Outer, 'Key>> * System.Linq.Expressions.Expression<Func<'Inner, 'Key>> * System.Linq.Expressions.Expression<Func<'Outer, 'Inner, 'Result>> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Linq.IQueryable<'Result>
<Extension()>
Public Function Join(Of TOuter, TInner, TKey, TResult) (outer As IQueryable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Expression(Of Func(Of TOuter, TKey)), innerKeySelector As Expression(Of Func(Of TInner, TKey)), resultSelector As Expression(Of Func(Of TOuter, TInner, TResult)), comparer As IEqualityComparer(Of TKey)) As IQueryable(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
IQueryable<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
Expression<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
Expression<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
Expression<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>

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

傳回

IQueryable<TResult>

IQueryable<T>,其具有透過對兩個序列執行內部聯結所取得之型別 TResult 的項目。An IQueryable<T> that has elements of type TResult obtained by performing an inner join on two sequences.

例外狀況

outerinnerouterKeySelectorinnerKeySelectorresultSelectornullouter or inner or outerKeySelector or innerKeySelector or resultSelector is null.

備註

這個方法至少有一個類型Expression<TDelegate>的參數, 其類型引數是其中一個Func<T,TResult>類型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 針對這些參數, 您可以傳入 lambda 運算式, 它會編譯成Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

方法會產生, 其代表以Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>)結構化泛型方法的方式呼叫本身。 MethodCallExpression Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>)The Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) method generates a MethodCallExpression that represents calling Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) itself as a constructed generic method. 然後, 它會MethodCallExpression將傳遞CreateQuery<TElement>(Expression)至由Provider outer參數IQueryProvider的屬性所表示之的方法。It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the outer parameter.

因執行代表呼叫Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>)之運算式樹狀架構而產生的查詢行為, 取決於outer參數類型的實作為。The query behavior that occurs as a result of executing an expression tree that represents calling Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) depends on the implementation of the type of the outer parameter. 預期的行為是內部聯結的行為。The expected behavior is that of an inner join. 和函式是用來分別從outerinner提取金鑰。 innerKeySelector outerKeySelectorThe outerKeySelector and innerKeySelector functions are used to extract keys from outer and inner, respectively. 這些索引鍵會使用comparer來比較是否相等。These keys are compared for equality by using comparer. 比較的結果會用來為中符合inner outer專案之中的每個專案建立相符的配對。The outcome of the comparisons is used to create a matching pair for each element in inner that matches an element in outer. resultSelector然後叫用函式, 從每一對相符的元素投影結果物件。Then the resultSelector function is invoked to project a result object from each pair of matching elements.

適用於