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

Definizione

Correla gli elementi di due sequenze in base alle chiavi corrispondente.Correlates the elements of two sequences based on matching keys.

Overload

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>>)

Correla gli elementi di due sequenze in base alle chiavi corrispondente.Correlates the elements of two sequences based on matching keys. Per confrontare le chiavi viene usato l'operatore di confronto uguaglianze predefinito.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>)

Correla gli elementi di due sequenze in base alle chiavi corrispondente.Correlates the elements of two sequences based on matching keys. Per confrontare le chiavi, viene usato un oggetto IEqualityComparer<T> specificato.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>>)

Correla gli elementi di due sequenze in base alle chiavi corrispondente.Correlates the elements of two sequences based on matching keys. Per confrontare le chiavi viene usato l'operatore di confronto uguaglianze predefinito.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)

Parametri di tipo

TOuter

Tipo degli elementi della prima sequenza.The type of the elements of the first sequence.

TInner

Tipo degli elementi della seconda sequenza.The type of the elements of the second sequence.

TKey

Tipo delle chiavi restituite dalle funzioni del selettore principale.The type of the keys returned by the key selector functions.

TResult

Tipo degli elementi di risultato.The type of the result elements.

Parametri

outer
IQueryable<TOuter>

Prima sequenza da unire.The first sequence to join.

inner
IEnumerable<TInner>

Sequenza da unire alla prima sequenza.The sequence to join to the first sequence.

outerKeySelector
Expression<Func<TOuter,TKey>>

Funzione per estrarre la chiave di aggiunta da ogni elemento della prima sequenza.A function to extract the join key from each element of the first sequence.

innerKeySelector
Expression<Func<TInner,TKey>>

Funzione per estrarre la chiave di aggiunta da ogni elemento della seconda sequenza.A function to extract the join key from each element of the second sequence.

resultSelector
Expression<Func<TOuter,TInner,TResult>>

Funzione per creare un elemento di risultato da due elementi corrispondenti.A function to create a result element from two matching elements.

Restituisce

IQueryable<TResult>

Un' IQueryable<T> che contiene elementi di tipo TResult ottenuti eseguendo un inner join sulle due sequenze.An IQueryable<T> that has elements of type TResult obtained by performing an inner join on two sequences.

Eccezioni

outer oppure inner oppure outerKeySelector oppure innerKeySelector oppure resultSelector è null.outer or inner or outerKeySelector or innerKeySelector or resultSelector is null.

Esempi

Esempio di codice seguente viene illustrato come utilizzare Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) per eseguire un inner join delle due sequenze in base a una chiave comune.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

Commenti

Questo metodo ha almeno un parametro di tipo Expression<TDelegate> il cui argomento tipo è uno del Func<T,TResult> tipi.This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. Per questi parametri, è possibile passare in un'espressione lambda e verrà compilata per un Expression<TDelegate>.For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

Il Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) metodo genera un MethodCallExpression che rappresenta una chiamata Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) stesso come un metodo generico costruito.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. Passa quindi il MethodCallExpression per il CreateQuery<TElement>(Expression) metodo del IQueryProvider rappresentato dal Provider proprietà del outer parametro.It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the outer parameter.

Il comportamento delle query che si verifica in seguito all'esecuzione di un albero delle espressioni che rappresenta una chiamata Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>) dipende dall'implementazione del tipo del outer parametro.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. Il comportamento previsto è quello di un inner join.The expected behavior is that of an inner join. Il outerKeySelector e innerKeySelector funzioni vengono usate per estrarre le chiavi dal outer e inner, rispettivamente.The outerKeySelector and innerKeySelector functions are used to extract keys from outer and inner, respectively. Queste chiavi vengono confrontate per verificarne l'uguaglianza per far corrispondere gli elementi da ogni sequenza.These keys are compared for equality to match elements from each sequence. Una coppia di elementi verrà archiviata per ogni elemento nella inner che corrisponde a un elemento in outer.A pair of elements is stored for each element in inner that matches an element in outer. Il resultSelector funzione viene richiamata per proiettare un oggetto risultato di ogni coppia di elementi corrispondenti.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>)

Correla gli elementi di due sequenze in base alle chiavi corrispondente.Correlates the elements of two sequences based on matching keys. Per confrontare le chiavi, viene usato un oggetto IEqualityComparer<T> specificato.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)

Parametri di tipo

TOuter

Tipo degli elementi della prima sequenza.The type of the elements of the first sequence.

TInner

Tipo degli elementi della seconda sequenza.The type of the elements of the second sequence.

TKey

Tipo delle chiavi restituite dalle funzioni del selettore principale.The type of the keys returned by the key selector functions.

TResult

Tipo degli elementi di risultato.The type of the result elements.

Parametri

outer
IQueryable<TOuter>

Prima sequenza da unire.The first sequence to join.

inner
IEnumerable<TInner>

Sequenza da unire alla prima sequenza.The sequence to join to the first sequence.

outerKeySelector
Expression<Func<TOuter,TKey>>

Funzione per estrarre la chiave di aggiunta da ogni elemento della prima sequenza.A function to extract the join key from each element of the first sequence.

innerKeySelector
Expression<Func<TInner,TKey>>

Funzione per estrarre la chiave di aggiunta da ogni elemento della seconda sequenza.A function to extract the join key from each element of the second sequence.

resultSelector
Expression<Func<TOuter,TInner,TResult>>

Funzione per creare un elemento di risultato da due elementi corrispondenti.A function to create a result element from two matching elements.

comparer
IEqualityComparer<TKey>

Oggetto IEqualityComparer<T> per la codifica hash e il confronto delle chiavi.An IEqualityComparer<T> to hash and compare keys.

Restituisce

IQueryable<TResult>

Un' IQueryable<T> che contiene elementi di tipo TResult ottenuti eseguendo un inner join sulle due sequenze.An IQueryable<T> that has elements of type TResult obtained by performing an inner join on two sequences.

Eccezioni

outer oppure inner oppure outerKeySelector oppure innerKeySelector oppure resultSelector è null.outer or inner or outerKeySelector or innerKeySelector or resultSelector is null.

Commenti

Questo metodo ha almeno un parametro di tipo Expression<TDelegate> il cui argomento tipo è uno del Func<T,TResult> tipi.This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. Per questi parametri, è possibile passare in un'espressione lambda e verrà compilata per un Expression<TDelegate>.For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

Il Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) metodo genera un MethodCallExpression che rappresenta una chiamata Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) stesso come un metodo generico costruito.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. Passa quindi il MethodCallExpression per il CreateQuery<TElement>(Expression) metodo del IQueryProvider rappresentato dal Provider proprietà del outer parametro.It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the outer parameter.

Il comportamento delle query che si verifica in seguito all'esecuzione di un albero delle espressioni che rappresenta una chiamata Join<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,TInner,TResult>>, IEqualityComparer<TKey>) dipende dall'implementazione del tipo del outer parametro.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. Il comportamento previsto è quello di un inner join.The expected behavior is that of an inner join. Il outerKeySelector e innerKeySelector funzioni vengono usate per estrarre le chiavi dal outer e inner, rispettivamente.The outerKeySelector and innerKeySelector functions are used to extract keys from outer and inner, respectively. Queste chiavi vengono confrontate per verificarne l'uguaglianza tramite comparer.These keys are compared for equality by using comparer. Il risultato dei confronti viene utilizzato per creare una coppia corrispondente per ogni elemento nella inner che corrisponde a un elemento in outer.The outcome of the comparisons is used to create a matching pair for each element in inner that matches an element in outer. Il resultSelector funzione viene richiamata per proiettare un oggetto risultato di ogni coppia di elementi corrispondenti.Then the resultSelector function is invoked to project a result object from each pair of matching elements.

Si applica a