Queryable.ThenBy 方法
定義
依遞增順序,執行序列中項目的後續排序作業。Performs a subsequent ordering of the elements in a sequence in ascending order.
多載
ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) |
使用指定的比較子,依遞增順序執行序列中項目的後續排序作業。Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer. |
ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) |
依據索引鍵,按遞增順序執行序列中項目的後續排序作業。Performs a subsequent ordering of the elements in a sequence in ascending order according to a key. |
ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>)
使用指定的比較子,依遞增順序執行序列中項目的後續排序作業。Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer.
public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
static System::Linq::IOrderedQueryable<TSource> ^ ThenBy(System::Linq::IOrderedQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TKey> ^> ^ keySelector, System::Collections::Generic::IComparer<TKey> ^ comparer);
public static System.Linq.IOrderedQueryable<TSource> ThenBy<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector, System.Collections.Generic.IComparer<TKey> comparer);
public static System.Linq.IOrderedQueryable<TSource> ThenBy<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector, System.Collections.Generic.IComparer<TKey>? comparer);
static member ThenBy : System.Linq.IOrderedQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Key>> * System.Collections.Generic.IComparer<'Key> -> System.Linq.IOrderedQueryable<'Source>
<Extension()>
Public Function ThenBy(Of TSource, TKey) (source As IOrderedQueryable(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey)), comparer As IComparer(Of TKey)) As IOrderedQueryable(Of TSource)
類型參數
- TSource
source
項目的類型。The type of the elements of source
.
- TKey
keySelector
表示之函式所傳回索引鍵的型別。The type of the key returned by the function represented by keySelector
.
參數
- source
- IOrderedQueryable<TSource>
包含要排序之項目的 IOrderedQueryable<T>。An IOrderedQueryable<T> that contains elements to sort.
- keySelector
- Expression<Func<TSource,TKey>>
用來從各個項目擷取索引鍵的函式。A function to extract a key from each element.
- comparer
- IComparer<TKey>
用來比較金鑰的 IComparer<T>。An IComparer<T> to compare keys.
傳回
- IOrderedQueryable<TSource>
依據索引鍵排序其項目的 IOrderedQueryable<T>。An IOrderedQueryable<T> whose elements are sorted according to a key.
例外狀況
source
、keySelector
或 comparer
為 null
。source
or keySelector
or comparer
is null
.
備註
這個方法至少有一個類型的參數 Expression<TDelegate> ,其型別引數是其中一種 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,並將其編譯為 Expression<TDelegate> 。For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.
ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>)方法 MethodCallExpression 會產生,代表呼叫 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) 本身做為已建立的泛型方法。The ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) method generates a MethodCallExpression that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) itself as a constructed generic method. 然後,它會將傳遞 MethodCallExpression 給以 CreateQuery<TElement>(Expression) 參數的屬性所表示的方法 IQueryProvider Provider source
。It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source
parameter. 呼叫的結果 CreateQuery<TElement>(Expression) 會轉換成型別 IOrderedQueryable<T> 並傳回。The result of calling CreateQuery<TElement>(Expression) is cast to type IOrderedQueryable<T> and returned.
執行表示呼叫的運算式樹狀架構所產生的查詢行為, ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) 取決於參數類型的實作為 source
。The query behavior that occurs as a result of executing an expression tree that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) depends on the implementation of the type of the source
parameter. 預期的行為是它會 source
根據在 keySelector
的每個專案上叫用所取得的索引鍵,執行專案的次要排序 source
。The expected behavior is that it performs a secondary sort of the elements of source
based on the key obtained by invoking keySelector
on each element of source
. 所有先前建立的排序次序都會保留下來。All previously established sort orders are preserved. comparer
參數是用來比較索引鍵值。The comparer
parameter is used to compare key values.
適用於
ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>)
依據索引鍵,按遞增順序執行序列中項目的後續排序作業。Performs a subsequent ordering of the elements in a sequence in ascending order according to a key.
public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
static System::Linq::IOrderedQueryable<TSource> ^ ThenBy(System::Linq::IOrderedQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TKey> ^> ^ keySelector);
public static System.Linq.IOrderedQueryable<TSource> ThenBy<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector);
static member ThenBy : System.Linq.IOrderedQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Key>> -> System.Linq.IOrderedQueryable<'Source>
<Extension()>
Public Function ThenBy(Of TSource, TKey) (source As IOrderedQueryable(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey))) As IOrderedQueryable(Of TSource)
類型參數
- TSource
source
項目的類型。The type of the elements of source
.
- TKey
keySelector
表示之函式所傳回索引鍵的型別。The type of the key returned by the function represented by keySelector
.
參數
- source
- IOrderedQueryable<TSource>
包含要排序之項目的 IOrderedQueryable<T>。An IOrderedQueryable<T> that contains elements to sort.
- keySelector
- Expression<Func<TSource,TKey>>
用來從各個項目擷取索引鍵的函式。A function to extract a key from each element.
傳回
- IOrderedQueryable<TSource>
依據索引鍵排序其項目的 IOrderedQueryable<T>。An IOrderedQueryable<T> whose elements are sorted according to a key.
例外狀況
source
或 keySelector
為 null
。source
or keySelector
is null
.
範例
下列程式碼範例示範如何使用 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) 來執行序列中元素的次要順序。The following code example demonstrates how to use ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) to perform a secondary ordering of the elements in a sequence.
string[] fruits = { "grape", "passionfruit", "banana", "apple",
"orange", "raspberry", "mango", "blueberry" };
// Sort the strings first by their length and then
// alphabetically by passing the identity selector function.
IEnumerable<string> query =
fruits.AsQueryable()
.OrderBy(fruit => fruit.Length).ThenBy(fruit => fruit);
foreach (string fruit in query)
Console.WriteLine(fruit);
/*
This code produces the following output:
apple
grape
mango
banana
orange
blueberry
raspberry
passionfruit
*/
Dim fruits() As String = _
{"grape", "passionfruit", "banana", "mango", _
"orange", "raspberry", "apple", "blueberry"}
' Sort the strings first by their length and then
' alphabetically by passing the identity selector function.
Dim query = fruits.AsQueryable() _
.OrderBy(Function(fruit) fruit.Length).ThenBy(Function(fruit) fruit)
' Display the results.
Dim output As New System.Text.StringBuilder
For Each fruit As String In query
output.AppendLine(fruit)
Next
MsgBox(output.ToString())
'This code produces the following output:
'apple
'grape
'mango
'banana
'orange
'blueberry
'raspberry
'passionfruit
備註
這個方法至少有一個類型的參數 Expression<TDelegate> ,其型別引數是其中一種 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,並將其編譯為 Expression<TDelegate> 。For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.
ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>)方法 MethodCallExpression 會產生,代表呼叫 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) 本身做為已建立的泛型方法。The ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) method generates a MethodCallExpression that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) itself as a constructed generic method. 然後,它會將傳遞 MethodCallExpression 給以 CreateQuery<TElement>(Expression) 參數的屬性所表示的方法 IQueryProvider Provider source
。It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source
parameter. 呼叫的結果 CreateQuery<TElement>(Expression) 會轉換成型別 IOrderedQueryable<T> 並傳回。The result of calling CreateQuery<TElement>(Expression) is cast to type IOrderedQueryable<T> and returned.
執行表示呼叫的運算式樹狀架構所產生的查詢行為, ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) 取決於參數類型的實作為 source
。The query behavior that occurs as a result of executing an expression tree that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) depends on the implementation of the type of the source
parameter. 預期的行為是它會 source
根據在 keySelector
的每個專案上叫用所取得的索引鍵,執行專案的次要排序 source
。The expected behavior is that it performs a secondary sort of the elements of source
based on the key obtained by invoking keySelector
on each element of source
. 所有先前建立的排序次序都會保留下來。All previously established sort orders are preserved.