C#-WebForm-LinQ（一）-LinQ：语言集成查询（Language Integrated Query）-增删改查、属性扩展

LinQ-语言集成查询（Language Integrated Query）　　

高集成化的数据库访问技术

LINQ 2 SQL 实际是将数据库的表映射成程序中的类

会把数据库的表名原封不动的变成类名

数据库的列名原封不动的变成字段名/属性名

所有的操作都是通过Linq自动生成的一个上下文对象来进行操作的

Linq的名字+"DataContext"

一个数据库对应一个Linq

去除数据访问类的简便开发方式：

不需要新建数据库访问类，直接用< using(DataClassesContext con = new DataClassContext()){} >进行数据库访问

一、后台绑定数据　　数据查询 con.Users; 或 con.Users.ToList();

public partial class Default3 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            using (DataClassesDataContext con = new DataClassesDataContext())
            {
                Repeater1.DataSource = con.Users.ToList();
                Repeater1.DataBind();
            }
        }
    }
}

二、删除代码　　数据删除 con.Users.DeleteOnSubmit(u); 参数是要删除的完整数据

满足条件  r => r.username == Request["uname"]  r是循环遍历数据的每一条数据

FirstOnDefault()  返回第一个或没有时返回默认值null  

public partial class Delete : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            using (DataClassesDataContext con = new DataClassesDataContext())
            {
                //通过提交过来的用户名查找整条用户信息
                Users u = con.Users.Where(r => r.username == Request["uname"]).FirstOrDefault();
                //整条信息进行删除
                con.Users.DeleteOnSubmit(u);
                con.SubmitChanges();
                //跳回主页面
                Response.Redirect("Default3.aspx");
            }
        }
    }

}

三、添加数据

con.Users.InsertOnSubmit(u);　　con.SubmitChanges();

public partial class Insert : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Button1.Click += Button1_Click;
    }

    void Button1_Click(object sender, EventArgs e)
    {
        //要添加的数据
        Users u = new Users();
        u.username = TextBox1.Text;
        u.password = TextBox2.Text;
        u.nickname = TextBox3.Text;
        u.sex = Convert.ToBoolean(TextBox4.Text);
        u.birthday = Convert.ToDateTime(TextBox5.Text);
        u.nation = TextBox6.Text;
        u.@class = TextBox7.Text;

        //打开数据库进行操作：添加数据
        using(DataClassesDataContext con=new DataClassesDataContext ())
        {
            con.Users.InsertOnSubmit(u);
            con.SubmitChanges();
            Response.Redirect("Default3.aspx");
        }
    }

}

四、修改数据　　查询出数据然后进行修改

public partial class Update : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //要修改的数据
            using (DataClassesDataContext con = new DataClassesDataContext())
            {
                Users u = con.Users.Where(r => r.username == Request["uname"]).FirstOrDefault();
                if (u != null)
                {
                    TextBox1.Text = u.username;
                    TextBox2.Text = u.password;
                    TextBox3.Text = u.nickname;
                    TextBox4.Text = u.sex.ToString();
                    TextBox5.Text = u.birthday.ToString();
                    TextBox6.Text = u.nation;
                    TextBox7.Text = u.@class;
                }
                else
                    Response.Redirect("Default3.aspx?tt=33");
            }
        }

        Button1.Click += Button1_Click;
    }

    void Button1_Click(object sender, EventArgs e)
    {
        //修改后的数据
        using (DataClassesDataContext con = new DataClassesDataContext())
        {
            Users u = con.Users.Where(r => r.username == TextBox1.Text).FirstOrDefault();
            u.username = TextBox1.Text;
            u.password = TextBox2.Text;
            u.nickname = TextBox3.Text;
            u.sex = Convert.ToBoolean(TextBox4.Text);
            u.birthday = Convert.ToDateTime(TextBox5.Text);
            u.nation = TextBox6.Text;
            u.@class = TextBox7.Text;
            //进行修改
            con.SubmitChanges();
            Response.Redirect("Default3.aspx");
        }
    }

}

=============================================

基础知识：如何新建LinQ to SQL 类

一、新建

二、点击“服务器资源管理器”

三、点击“连接到数据库”

 四、选择

五、将需要的表拖拽至界面，系统自动生成实体类

=============================================

高级版操作-去除数据库访问类：

一、展示页面代码：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <style>
        * {
            padding: 0px;
            margin: 0px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            用户名：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            昵称：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            出生年份：<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            民族：<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
            班级：<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
            <asp:Button ID="Button1" runat="server" Text="查询" />
            <br />
            <table style=" 100%; text-align: center;">
                <tr style=" color: white;">
                    <td>编号</td>
                    <td>用户名</td>
                    <td>密码</td>
                    <td>昵称</td>
                    <td>性别</td>
                    <td>生日</td>
                    <td>民族</td>
                    <td>班级</td>
                    <td>操作</td>
                </tr>
                <asp:Repeater ID="Repeater1" runat="server">
                    <ItemTemplate>
                        <tr>
                            <td><%#Eval("ids") %></td>
                            <td><%#Eval("username") %></td>
                            <td><%#Eval("password") %></td>
                            <td><%#Eval("nickname") %></td>
                            <td><%#Eval("sex") %></td>
                            <td><%#Eval("birthday") %></td>
                            <td><%#Eval("nation") %></td>
                            <td><%#Eval("class") %></td>
                            <td>
                                <a href="Update.aspx?uname=<%#Eval("username") %>">修改</a>
                                <a href="Delete.aspx?uname=<%#Eval("username") %>">修改</a>
                            </td>
                        </tr>
                    </ItemTemplate>
                </asp:Repeater>
            </table>
            <a href="Insert.aspx">添加</a>
        </div>
    </form>
</body>
</html>

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <style>
        * {
            padding: 0px;
            margin: 0px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            用户名：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            昵称：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            出生年份：<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            民族：<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
            班级：<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
            <asp:Button ID="Button1" runat="server" Text="查询" />
            <br />
            <table style=" 100%; text-align: center;">
                <tr style=" color: white;">
                    <td>编号</td>
                    <td>用户名</td>
                    <td>密码</td>
                    <td>昵称</td>
                    <td>性别</td>
                    <td>生日</td>
                    <td>民族</td>
                    <td>班级</td>
                    <td>操作</td>
                </tr>
                <asp:Repeater ID="Repeater1" runat="server">
                    <ItemTemplate>
                        <tr>
                            <td><%#Eval("ids") %></td>
                            <td><%#Eval("username") %></td>
                            <td><%#Eval("password") %></td>
                            <td><%#Eval("nickname") %></td>
                            <td><%#Eval("sex") %></td>
                            <td><%#Eval("birthday") %></td>
                            <td><%#Eval("nation") %></td>
                            <td><%#Eval("class") %></td>
                            <td>
                                <a href="Update.aspx?uname=<%#Eval("username") %>">修改</a>
                                <a href="Delete.aspx?uname=<%#Eval("username") %>">修改</a>
                            </td>
                        </tr>
                    </ItemTemplate>
                </asp:Repeater>
            </table>
            <a href="Insert.aspx">添加</a>
        </div>
    </form>
</body>
</html>

二、后台数据绑定

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default3 : System.Web.UI.Page
{
    DataClassesDataContext con = new DataClassesDataContext();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            using (con)
            {
                Repeater1.DataSource = con.Users.ToList();
                Repeater1.DataBind();
            }
        }
    }



}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default3 : System.Web.UI.Page
{
    DataClassesDataContext con = new DataClassesDataContext();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            using (con)
            {
                Repeater1.DataSource = con.Users.ToList();
                Repeater1.DataBind();
            }
        }
    }



}

 三、using(){}增删改查（同上）

=============================================

低阶版操作-新建数据库访问类：

一、展示页面代码：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <style>
        * {
            padding: 0px;
            margin: 0px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            用户名：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            昵称：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            出生年份：<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            民族：<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
            班级：<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
            <asp:Button ID="Button1" runat="server" Text="查询" />
            <br />
            <asp:Repeater ID="Repeater1" runat="server">
                <HeaderTemplate>
                    <table style=" 100%; text-align: center;">
                        <tr style=" color: white;">
                            <td>编号</td>
                            <td>用户名</td>
                            <td>密码</td>
                            <td>昵称</td>
                            <td>性别</td>
                            <td>生日</td>
                            <td>民族</td>
                            <td>班级</td>
                            <td>操作</td>
                        </tr>
                </HeaderTemplate>
                <ItemTemplate>
                    <tr>
                        <td><%#Eval("ids") %></td>
                        <td><%#Eval("username") %></td>
                        <td><%#Eval("password") %></td>
                        <td><%#Eval("nickname") %></td>
                        <td><%#Eval("sex") %></td>
                        <td><%#Eval("birthday") %></td>
                        <td><%#Eval("nation") %></td>
                        <td><%#Eval("class") %></td>
                        <td>
                            <a href="Update.aspx?uname=<%#Eval("username") %>">修改</a>
                            <a href="Delete.aspx?uname=<%#Eval("username") %>">修改</a>
                        </td>
                    </tr>
                </ItemTemplate>
                <FooterTemplate>
                    </table>
                </FooterTemplate>
            </asp:Repeater>
            <a href="Insert.aspx">添加</a>
        </div>
    </form>
</body>
</html>

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <style>
        * {
            padding: 0px;
            margin: 0px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            用户名：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            昵称：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            出生年份：<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            民族：<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
            班级：<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
            <asp:Button ID="Button1" runat="server" Text="查询" />
            <br />
            <asp:Repeater ID="Repeater1" runat="server">
                <HeaderTemplate>
                    <table style=" 100%; text-align: center;">
                        <tr style=" color: white;">
                            <td>编号</td>
                            <td>用户名</td>
                            <td>密码</td>
                            <td>昵称</td>
                            <td>性别</td>
                            <td>生日</td>
                            <td>民族</td>
                            <td>班级</td>
                            <td>操作</td>
                        </tr>
                </HeaderTemplate>
                <ItemTemplate>
                    <tr>
                        <td><%#Eval("ids") %></td>
                        <td><%#Eval("username") %></td>
                        <td><%#Eval("password") %></td>
                        <td><%#Eval("nickname") %></td>
                        <td><%#Eval("sex") %></td>
                        <td><%#Eval("birthday") %></td>
                        <td><%#Eval("nation") %></td>
                        <td><%#Eval("class") %></td>
                        <td>
                            <a href="Update.aspx?uname=<%#Eval("username") %>">修改</a>
                            <a href="Delete.aspx?uname=<%#Eval("username") %>">修改</a>
                        </td>
                    </tr>
                </ItemTemplate>
                <FooterTemplate>
                    </table>
                </FooterTemplate>
            </asp:Repeater>
            <a href="Insert.aspx">添加</a>
        </div>
    </form>
</body>
</html>

二、新建 LinQ to SQL 类

三、新建数据访问类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
/// DataClassesData 的摘要说明
/// </summary>
public class DataClassesData
{
    DataClassesDataContext con = null;
    public DataClassesData()
    {
        con = new DataClassesDataContext();
    }
    //查询
    public List<Users> Select()
    {
        return con.Users.ToList();
    }

    //添加
    public void Insert(Users u)
    {
        con.Users.InsertOnSubmit(u);
        con.SubmitChanges();
    }

    //删除
    public void Delete(string uname)
    {
        Users u = con.Users.Where(r => r.username == uname).FirstOrDefault();
        if (u != null)
        {
            con.Users.DeleteOnSubmit(u);
            con.SubmitChanges();
        }
    }

}

　　

==================================================

属性扩展：

新建一个类 → partial → 删除其结构函数 → 进行属性扩展