c# LINQ查詢操作符實例操作總結2

介紹
    ·Distinct - 過濾集合中的相同項；延遲
    ·Union - 連接不同集合，自動過濾相同項；延遲
    ·Concat - 連接不同集合，不會自動過濾相同項；延遲
    ·Intersect - 獲取不同集合的相同項（交集）；延遲
    ·Except - 從某集合中刪除其與另一個集合中相同的項；延遲
    ·Skip - 跳過集合的前n個元素；延遲
    ·Take - 獲取集合的前n個元素；延遲
    ·SkipWhile - 直到某一條件成立就停止跳過；延遲
    ·TakeWhile - 直到某一條件成立就停止獲取；延遲
    ·Single - 根據表達式返回集合中的某一元素；不延遲
    ·SingleOrDefault - 根據表達式返回集合中的某一元素（如果沒有則返回默認值）；不延遲
    ·Reverse - 對集合反向排序；延遲
    ·SelectMany - Select選擇（一對多）；延遲

示例
Summary2.aspx.cs

[csharp] view plain copy print ?

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;
using System.Collections.Generic;
using DAL;
public partial class LINQ_Summary2 : System.Web.UI.Page
{
NorthwindDataContext _ctx = new NorthwindDataContext();
string[] _ary = null;
protected void Page_Load(object sender, EventArgs e)
{
_ary = new string[] { "asp.net", "csharp", "xhtml", "css", "javascript", "wcf", "wpf",
"asp.net", "csharp", "xhtml", "css", "javascript",
"silverlight", "linq", "wf", "sqlserver", "asp.net ajax", "ssis", "ssas", "ssrs" };
// Distinct - 過濾集合中的相同項；延遲
Summary_Distinct();
// Union - 連接不同集合，自動過濾相同項；延遲
Summary_Union();
// Concat - 連接不同集合，不會自動過濾相同項；延遲
Summary_Concat();
// Intersect - 獲取不同集合的相同項（交集）；延遲
Summary_Intersect();
// Except - 從某集合中刪除其與另一個集合中相同的項；延遲
Summary_Except();
// Skip - 跳過集合的前n個元素；延遲
// Take - 獲取集合的前n個元素；延遲
Summary_Skip_Take();
// SkipWhile - 直到某一條件成立就停止跳過；延遲
// TakeWhile - 直到某一條件成立就停止獲取；延遲
Summary_SkipWhile_TakeWhile();
// Single - 根據表達式返回集合中的某一元素；不延遲
// SingleOrDefault - 根據表達式返回集合中的某一元素（如果沒有則返回默認值）；不延遲
Summary_Single_SingleOrDefault();
// Reverse - 對集合反向排序；延遲
Summary_Reverse();
// SelectMany - Select選擇（一對多）；延遲
Summary_SelectMany();
}
}

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;

using System.Collections.Generic;
using DAL;

public partial class LINQ_Summary2 : System.Web.UI.Page
{
    NorthwindDataContext _ctx = new NorthwindDataContext();
    string[] _ary = null;

    protected void Page_Load(object sender, EventArgs e)
    {
        _ary = new string[] { "asp.net", "csharp", "xhtml", "css", "javascript", "wcf", "wpf", 
            "asp.net", "csharp", "xhtml", "css", "javascript", 
            "silverlight", "linq", "wf", "sqlserver", "asp.net ajax", "ssis", "ssas", "ssrs" };

        // Distinct - 過濾集合中的相同項；延遲
        Summary_Distinct();

        // Union - 連接不同集合，自動過濾相同項；延遲
        Summary_Union();

        // Concat - 連接不同集合，不會自動過濾相同項；延遲
        Summary_Concat();

        // Intersect - 獲取不同集合的相同項（交集）；延遲
        Summary_Intersect();

        // Except - 從某集合中刪除其與另一個集合中相同的項；延遲
        Summary_Except();

        // Skip - 跳過集合的前n個元素；延遲
        // Take - 獲取集合的前n個元素；延遲
        Summary_Skip_Take();

        // SkipWhile - 直到某一條件成立就停止跳過；延遲
        // TakeWhile - 直到某一條件成立就停止獲取；延遲
        Summary_SkipWhile_TakeWhile();

        // Single - 根據表達式返回集合中的某一元素；不延遲
        // SingleOrDefault - 根據表達式返回集合中的某一元素（如果沒有則返回默認值）；不延遲
        Summary_Single_SingleOrDefault();

        // Reverse - 對集合反向排序；延遲
        Summary_Reverse();

        // SelectMany - Select選擇（一對多）；延遲
        Summary_SelectMany();
    }
}

Distinct - 過濾集合中的相同項；延遲

[csharp] view plain copy print ?

/// <summary>
/// Distinct - 過濾集合中的相同項；延遲
/// </summary>
void Summary_Distinct()
{
var ary = (from a in _ary
select a).Distinct();
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

/// <summary>
    /// Distinct - 過濾集合中的相同項；延遲
    /// </summary>
    void Summary_Distinct()
    {
        var ary = (from a in _ary
                   select a).Distinct();

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
asp.net
csharp
xhtml
css
javascript
wcf
wpf
silverlight
linq
wf
sqlserver
asp.net ajax
ssis
ssas
ssrs

Union - 連接不同集合，自動過濾相同項；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Union - 連接不同集合，自動過濾相同項；延遲
/// </summary>
void Summary_Union()
{
var ary = (from a in _ary
select a).Take(3).Union((from a in _ary
select a).Take(6));
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

/**//// <summary>
    /// Union - 連接不同集合，自動過濾相同項；延遲
    /// </summary>
    void Summary_Union()
    {
        var ary = (from a in _ary
                   select a).Take(3).Union((from a in _ary
                                            select a).Take(6));

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
asp.net
csharp
xhtml
css
javascript
wcf

Concat - 連接不同集合，不會自動過濾相同項；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Concat - 連接不同集合，不會自動過濾相同項；延遲
/// </summary>
void Summary_Concat()
{
var ary = (from a in _ary
select a).Take(3).Concat((from a in _ary
select a).Take(6));
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

 /**//// <summary>
    /// Concat - 連接不同集合，不會自動過濾相同項；延遲
    /// </summary>
    void Summary_Concat()
    {
        var ary = (from a in _ary
                   select a).Take(3).Concat((from a in _ary
                                             select a).Take(6));

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
asp.net
csharp
xhtml
asp.net
csharp
xhtml
css
javascript
wcf

Intersect - 獲取不同集合的相同項（交集）；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Intersect - 獲取不同集合的相同項（交集）；延遲
/// </summary>
void Summary_Intersect()
{
var ary = (from a in _ary
select a).Take(3).Intersect((from a in _ary
select a).Skip(1).Take(3));
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

    /**//// <summary>
    /// Intersect - 獲取不同集合的相同項（交集）；延遲
    /// </summary>
    void Summary_Intersect()
    {
        var ary = (from a in _ary
                   select a).Take(3).Intersect((from a in _ary
                                                select a).Skip(1).Take(3));

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
csharp
xhtml

Except - 從某集合中刪除其與另一個集合中相同的項；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Except - 從某集合中刪除其與另一個集合中相同的項；延遲
/// </summary>
void Summary_Except()
{
var ary = (from a in _ary
select a).Take(3).Except((from a in _ary
select a).Skip(1).Take(3));
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

    /**//// <summary>
    /// Except - 從某集合中刪除其與另一個集合中相同的項；延遲
    /// </summary>
    void Summary_Except()
    {
        var ary = (from a in _ary
                   select a).Take(3).Except((from a in _ary
                                             select a).Skip(1).Take(3));

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
asp.net

Skip - 跳過集合的前n個元素；延遲
Take - 獲取集合的前n個元素；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Skip - 跳過集合的前n個元素；延遲
/// Take - 獲取集合的前n個元素；延遲
/// </summary>
void Summary_Skip_Take()
{
var ary = (from a in _ary
select a).Skip(2).Take(3);
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

    /**//// <summary>
    /// Skip - 跳過集合的前n個元素；延遲
    /// Take - 獲取集合的前n個元素；延遲
    /// </summary>
    void Summary_Skip_Take()
    {
        var ary = (from a in _ary
                   select a).Skip(2).Take(3);

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
xhtml
css
javascript

SkipWhile - 直到某一條件成立就停止跳過；延遲
TakeWhile - 直到某一條件成立就停止獲取；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// SkipWhile - 直到某一條件成立就停止跳過；延遲
/// TakeWhile - 直到某一條件成立就停止獲取；延遲
/// </summary>
void Summary_SkipWhile_TakeWhile()
{
var ary = (from a in _ary
select a).SkipWhile(s => s.Length < 8).TakeWhile(s => s.Length > 2);
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

    /**//// <summary>
    /// SkipWhile - 直到某一條件成立就停止跳過；延遲
    /// TakeWhile - 直到某一條件成立就停止獲取；延遲
    /// </summary>
    void Summary_SkipWhile_TakeWhile()
    {
        var ary = (from a in _ary
                   select a).SkipWhile(s => s.Length < 8).TakeWhile(s => s.Length > 2);

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
javascript
wcf
wpf
asp.net
csharp
xhtml
css
javascript
silverlight
linq

Single - 根據表達式返回集合中的某一元素；不延遲
SingleOrDefault - 根據表達式返回集合中的某一元素（如果沒有則返回默認值）；不延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Single - 根據表達式返回集合中的某一元素；不延遲
/// SingleOrDefault - 根據表達式返回集合中的某一元素（如果沒有則返回默認值）；不延遲
/// </summary>
void Summary_Single_SingleOrDefault()
{
string s = (from a in _ary
select a).Single(a => a == "silverlight");
// string s = (from a in _ary
// select a).SingleOrDefault(a => a == "xxx");
// s == null
result.InnerHtml += s + " ";
result.InnerHtml += " ";
}

    /**//// <summary>
    /// Single - 根據表達式返回集合中的某一元素；不延遲
    /// SingleOrDefault - 根據表達式返回集合中的某一元素（如果沒有則返回默認值）；不延遲
    /// </summary>
    void Summary_Single_SingleOrDefault()
    {
        string s = (from a in _ary
                    select a).Single(a => a == "silverlight");
        // string s = (from a in _ary
        //             select a).SingleOrDefault(a => a == "xxx");
        // s == null

        result.InnerHtml += s + "<br />";
        result.InnerHtml += "<br />";
    }

運行結果
silverlight

Reverse - 對集合反向排序；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// Reverse - 對集合反向排序；延遲
/// </summary>
void Summary_Reverse()
{
var ary = (from a in _ary
orderby a.Length ascending
select a).Reverse();
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

    /**//// <summary>
    /// Reverse - 對集合反向排序；延遲
    /// </summary>
    void Summary_Reverse()
    {
        var ary = (from a in _ary
                   orderby a.Length ascending
                   select a).Reverse();

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
asp.net ajax
silverlight
javascript
javascript
sqlserver
asp.net
asp.net
csharp
csharp
xhtml
xhtml
ssrs
ssas
ssis
linq
css
wpf
wcf
css
wf

SelectMany - Select選擇（一對多）；延遲

[csharp] view plain copy print ?

/**//// <summary>
/// SelectMany - Select選擇（一對多）；延遲
/// </summary>
void Summary_SelectMany()
{
var ary = (from a in _ary
where a.Contains(".")
select a).SelectMany(a => a.Split('.'));
foreach (string s in ary)
{
result.InnerHtml += s + " ";
}
result.InnerHtml += " ";
}

    /**//// <summary>
    /// SelectMany - Select選擇（一對多）；延遲
    /// </summary>
    void Summary_SelectMany()
    {
        var ary = (from a in _ary
                   where a.Contains(".")
                   select a).SelectMany(a => a.Split('.'));

        foreach (string s in ary)
        {
            result.InnerHtml += s + "<br />";
        }
        result.InnerHtml += "<br />";
    }

運行結果
asp
net
asp
net
asp
net ajax

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