排序資料

發行項
08/21/2008

更新：2007 年 11 月

排序作業會根據一個或多個屬性來排序序列中的項目。第一個排序準則會對項目執行主要排序。而透過指定第二個排序準則，可以排序每個主要排序群組內的項目。

下圖顯示對字元序列執行字母排序作業的結果。

LINQ 排序作業

下節會列出排序資料的標準查詢運算子方法。

方法

方法名稱	說明	C# 查詢運算式語法	Visual Basic 查詢運算式語法	詳細資訊
OrderBy	將值依遞增順序排序。	orderby	Order By	Enumerable.OrderBy Queryable.OrderBy
OrderByDescending	將值依遞減順序排序。	orderby … descending	Order By … Descending	Enumerable.OrderByDescending Queryable.OrderByDescending
ThenBy	以遞增順序執行次要排序。	orderby …, …	Order By …, …	Enumerable.ThenBy Queryable.ThenBy
ThenByDescending	以遞減順序執行次要排序。	orderby …, … descending	Order By …, … Descending	Enumerable.ThenByDescending Queryable.ThenByDescending
Reverse	反轉集合中項目的順序。	不適用。	不適用。	Enumerable.Reverse<TSource> Queryable.Reverse<TSource>

查詢運算式語法範例

主要排序範例

主要遞增排序

下列範例示範如何在 LINQ 查詢中使用 orderby (在 Visual Basic 中是 Order By) 子句，將陣列中的字串依長度遞增排序。

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Length _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output:

' the
' fox
' quick
' brown
' jumps

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Length
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    the
    fox
    quick
    brown
    jumps
*/

主要遞減排序

下一個範例示範如何在 LINQ 查詢中使用 orderbydescending (在 Visual Basic 中是 Order By Descending) 子句，將字串依第一個字母遞減排序。

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Substring(0, 1) Descending _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output:

' the
' quick
' jumps
' fox
' brown

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Substring(0, 1) descending
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    the
    quick
    jumps
    fox
    brown
*/

次要排序範例

次要遞增排序

下列範例示範如何在 LINQ 查詢中使用 orderby (在 Visual Basic 中是 Order By) 子句，對陣列中的字串執行主要和次要排序。字串會先依長度做主要遞增排序，然後再依第一個字母做次要遞增排序。

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Length, word.Substring(0, 1) _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output:

' fox
' the
' brown
' jumps
' quick

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Length, word.Substring(0, 1)
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    fox
    the
    brown
    jumps
    quick
*/

次要遞減排序

下一個範例示範如何在 LINQ 查詢中使用 orderbydescending (在 Visual Basic 中是 Order By Descending) 子句，先依遞增順序做主要排序，再依遞減順序做次要排序。字串會先依長度做主要排序，然後再依第一個字母做次要排序。

Dim words() As String = {"the", "quick", "brown", "fox", "jumps"}

Dim sortQuery = From word In words _
                Order By word.Length, word.Substring(0, 1) Descending _
                Select word

Dim sb As New System.Text.StringBuilder()
For Each str As String In sortQuery
    sb.AppendLine(str)
Next

' Display the results.
MsgBox(sb.ToString())

' This code produces the following output:

' fox
' the
' quick
' jumps
' brown

string[] words = { "the", "quick", "brown", "fox", "jumps" };

IEnumerable<string> query = from word in words
                            orderby word.Length, word.Substring(0, 1) descending
                            select word;

foreach (string str in query)
    Console.WriteLine(str);

/* This code produces the following output:

    the
    fox
    quick
    jumps
    brown
*/