LINQ查詢運算符

投影是在其中一個對象被變換成僅特定性能一種全新的形式的操作。

運算符

描述

C#查詢表達式語法

VB查詢表達式語法

Select

操作轉換函數的基礎項目值

select

Select

SelectMany

操作項目的值是根據上的轉換函數，以及拼合成一個單一的序列的序列

使用多個from子句

使用多個from子句

Select的例子- 查詢表達式

C#

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Operators { class Program { static void Main(string[] args) { List words = new List() { "an", "apple", "a", "day" }; var query = from word in words select word.Substring(0, 1); foreach (string s in query) Console.WriteLine(s); Console.ReadLine(); } } }

VB

Module Module1 Sub Main() Dim words = New List(Of String) From {"an", "apple", "a", "day"} Dim query = From word In words Select word.Substring(0, 1) Dim sb As New System.Text.StringBuilder() For Each letter As String In query
sb.AppendLine(letter) Console.WriteLine(letter) Next Console.ReadLine() End Sub End Module

當在C＃或VB上面的代碼被編譯和執行時，它產生以下結果：

a
a
a
d

SelectMany例子- 查詢表達式

C#

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Operators { class Program { static void Main(string[] args) { List phrases = new List() { "an apple a day", "the quick brown fox" }; var query = from phrase in phrases from word in phrase.Split(' ') select word; foreach (string s in query) Console.WriteLine(s); Console.ReadLine(); } } }

VB

Module Module1 Sub Main() Dim phrases = New List(Of String) From {"an apple a day", "the quick brown fox"} Dim query = From phrase In phrases From word In phrase.Split(" "c) Select word Dim sb As New System.Text.StringBuilder() For Each str As String In query
sb.AppendLine(str) Console.WriteLine(str) Next Console.ReadLine() End Sub End Module

當在C＃或VB上面的代碼被編譯和執行時，它產生了以下結果：

an
apple
a
day
the
quick
brown
fox