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LINQ to SQL之面向对象的添加、查询、更新和删除

作者: webabcd  来源: 博客园  发布时间: 2008-09-26 11:20  阅读: 17646 次  推荐: 2   原文链接   [收藏]  

介绍
以Northwind为示例数据库,DLINQ(LINQ to SQL)之完全面向对象的添加操作、查询操作、更新操作和删除操作

示例
Sample.aspx

<%@ Page Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile=
      "
Sample.aspx.cs"
    Inherits
="LINQ_DLINQ_Sample" Title="面向对象的添加、查询、更新和删除" 
%>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    
<p>
        分类名称:
<asp:TextBox ID="txtCategoryName" runat="server"></asp:TextBox>
        
&nbsp;&nbsp; 分类描述:<asp:TextBox ID="txtDescription" runat="server"></asp:TextBox>
        
&nbsp;&nbsp;
        
<asp:Button ID="btnAdd" runat="server" Text="添加" OnClick="btnAdd_Click" />
    
</p>
    
<asp:GridView ID="gvCategory" runat="server" DataKeyNames="CategoryID"
              OnSelectedIndexChanged
="gvCategory_SelectedIndexChanged"        OnRowDeleting="gvCategory_RowDeleting" OnRowCancelingEdit="gvCategory_RowCancelingEdit"
        OnRowEditing
="gvCategory_RowEditing" OnRowUpdating="gvCategory_RowUpdating">
        
<Columns>
            
<asp:CommandField ShowSelectButton="True" ShowEditButton="True"
                   ShowDeleteButton
="True">
            
</asp:CommandField>
        
</Columns>
    
</asp:GridView>
    
<br />
    
<asp:DetailsView ID="dvProduct" runat="server" DataKeyNames="ProductID">
    
</asp:DetailsView>
</asp:Content>


Sample.aspx.cs

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 DAL;

public partial class LINQ_DLINQ_Sample : System.Web.UI.Page
{
    
// 实例化一个NorthwindDataContext(DataContext)
    NorthwindDataContext _ctx = new NorthwindDataContext();

    
protected void Page_Load(object sender, EventArgs e)
    
{
        
if (!Page.IsPostBack)
        
{
            BindCategory();
        }

    }


    
private void BindCategory()
    
{
        
// NorthwindDataContext对象的Category属性就是Category集合
        var categories = _ctx.Categories;

        gvCategory.DataSource 
= categories;
        gvCategory.DataBind();
    }


    
protected void btnAdd_Click(object sender, EventArgs e)
    
{
        
// 实例化一个Category
        Categories c = new Categories();

        
// 设置Category对象的相关属性
        c.CategoryName = txtCategoryName.Text;
        c.Description 
= txtDescription.Text;

        
// 使用NorthwindDataContext对象的InsertOnSubmit()方法添加Category对象
        _ctx.Categories.InsertOnSubmit(c);

        
// 生成并执行相应的SQL命令
        _ctx.SubmitChanges();

        gvCategory.EditIndex 
= -1;
        BindCategory();
    }


    
protected void gvCategory_SelectedIndexChanged(object sender, EventArgs e)
    
{
        
// 使用查询语法获得Product集合
        var products = from p in _ctx.Products
                       where p.Categories.CategoryID 
== (int)gvCategory.SelectedValue
                       select p;

        dvProduct.DataSource 
= products;
        dvProduct.DataBind();
    }


    
protected void gvCategory_RowDeleting(object sender, GridViewDeleteEventArgs e)
    
{
        
// 使用Single查询操作符获取指定的Category对象
        Categories category = _ctx.Categories.Single(c => c.CategoryID == (int)gvCategory.DataKeys[e.RowIndex].Value);

        
// 使用DeleteOnSubmit()方法删除NorthwindDataContext对象的Category集合中的指定Category对象
        _ctx.Categories.DeleteOnSubmit(category);

        
// 生成并执行相应的SQL命令
        _ctx.SubmitChanges();

        gvCategory.EditIndex 
= -1;
        BindCategory();
    }


    
protected void gvCategory_RowUpdating(object sender, GridViewUpdateEventArgs e)
    
{
        
// 使用查询语法和Single查询操作符获取指定的Category对象
        Categories category = (from c in _ctx.Categories
                             where c.CategoryID 
== (int)gvCategory.DataKeys[e.RowIndex].Value
                             select c).Single();

        
// 设置Category对象的相关属性
        category.CategoryName = ((TextBox)gvCategory.Rows[e.RowIndex].Cells[2].
                 Controls[
0]).Text;
        category.Description 
= ((TextBox)gvCategory.Rows[e.RowIndex].Cells[3].Controls[0]).Text;

        
// 生成并执行相应的SQL命令
        _ctx.SubmitChanges();

        gvCategory.EditIndex 
= -1;
        BindCategory();
    }


    
protected void gvCategory_RowEditing(object sender, GridViewEditEventArgs e)
    
{
        gvCategory.EditIndex 
= e.NewEditIndex;
        BindCategory();
    }


    
protected void gvCategory_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    
{
        gvCategory.EditIndex 
= -1;
        BindCategory();
    }

}


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