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linq to sql 学习（4）增删改查实例

2010-07-15 10:59 477 查看

看过了关于LINQ TO SQL 的介绍以及基本的原理之后，我们本次内容主要是做一个关于LINQ TO SQL 对数据库的增删改查，来加深我们对它的理解。

在创建项目之前，我们需要准备一个数据库表InStore.

(有关于次表的基础数据，请参考在前面的这篇博客《sql T_sql 通用的动态按月份统计输出》 )

备注：我们在做LINQ to SQL 之前，需要注意一个问题，就是创建的数据库表必须要有一个主键，本数据表InStore的主键是id

①，我们新建一个web应用程序项目，LinqDemo.

并添加新建项 LINQ to SQL 类，叫InStore.dbml ,如下图：

点击添加，接下来我们往该文件上添加一个数据库表：

此时我们会发现该文件的InStore.designer.cs 自动生成了很多相关的代码，有该数据表的实体类，操作类等。

②，为了方便我们后面做查询的需要，所以我们在这里顺便建一个PredicateBuilder.cs类，

代码如下：

using System;
using System.Linq;
using System.Linq.Expressions;
using System.Collections.Generic;
public static class PredicateBuilder
{
    public static Expression<Funcbool>> True()
    {
        return f => true;
    }
    public static Expression<Funcbool>> False()
    {
        return f => false;
    }
    public static Expression<Funcbool>> Or(this Expression<Funcbool>> expr1, Expression<Funcbool>> expr2)
    {
        var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
        return Expression.Lambda<Funcbool>>(Expression.Or(expr1.Body, invokedExpr), expr1.Parameters);
    }
    public static Expression<Funcbool>> And(this Expression<Funcbool>> expr1, Expression<Funcbool>> expr2)
    {
        var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
        return Expression.Lambda<Funcbool>>(Expression.And(expr1.Body, invokedExpr), expr1.Parameters);
    }
}

③，我们添加一个List.aspx页面，该页面的代码如下，

DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <table width="60%" border="1">
            <tr>
                <td>
                    id:<asp:TextBox ID="txt_id" runat="server">asp:TextBox>
                </td>
                <td>
                    名称<asp:TextBox ID="txt_proname" runat="server">asp:TextBox>
                </td>
                <td>
                    数量:<asp:TextBox ID="txt_insertcount" runat="server">asp:TextBox>
                </td>
                <td>
                    <asp:Button ID="btnQuery" runat="server" OnClick="btnQuery_Click" Text="查询" />
                    <asp:Button ID="btndelete" runat="server" Text="删除" OnClick="btndelete_Click" />
                    <asp:Button ID="btnAdd" runat="server" Text="添加" OnClick="btnAdd_Click" />
                    <asp:Button ID="btnUpdate" runat="server" Text="修改" OnClick="btnUpdate_Click" />
                </td>
            </tr>
            <tr>
                <td colspan="4">
                    <asp:GridView ID="GridView1" runat="server" Width="100%" AutoGenerateColumns="False">
                        <Columns>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <input type="checkbox" id="chk" runat="server" value='' />
                                ItemTemplate>
                                <ItemStyle Width="1px" />
                            asp:TemplateField>
                            <asp:BoundField DataField="id" HeaderText="id" />
                            <asp:BoundField DataField="proname" HeaderText="名称" />
                            <asp:BoundField DataField="insertday" HeaderText="入货时间" />
                            <asp:BoundField DataField="insertcount" HeaderText="入货数量" />
                        </Columns>
                        <RowStyle HorizontalAlign="Center" />
                    </asp:GridView>
                </td>
            </tr>
        </table>
    </div>
    </form>
</body>
</html>

List.aspx.cs后台代码如下：

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

namespace LinqDemo
{
    public partial class List : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            btndelete.Attributes.Add("onclick", "javascript:return window.confirm('确定删除吗？')");
            btnAdd.Attributes.Add("onclick", "javascript:return window.confirm('确定添加吗？')");
            if (!IsPostBack)
            {
                Bind();
            }
        }

        protected void btnQuery_Click(object sender, EventArgs e)
        {
            Bind();
        }
        /// <summary>
        /// 查询函数
        /// </summary>
        private void Bind()
        {
            var predicate = PredicateBuilder.True<InStore>();
            if (!string.IsNullOrEmpty(txt_proname.Text))
            {
                predicate = predicate.And(p => p.ProName.Contains(txt_proname.Text));
            }
            if (!string.IsNullOrEmpty(txt_insertcount.Text))
            {
                predicate = predicate.And(p => p.InsertCount.Equals(txt_insertcount.Text));
            }
            InStoreDataContext db = new InStoreDataContext();

            GridView1.DataSource = db.InStore.Where(predicate);
            GridView1.DataBind();
        }
        /// <summary>
        /// 添加函数
       /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btnAdd_Click(object sender, EventArgs e)
        {
            InStoreDataContext db = new InStoreDataContext();
            InStore store = new InStore();
            store.Id = int.Parse(txt_id.Text);
            store.InsertCount = int.Parse(txt_insertcount.Text);
            store.InsertDay = DateTime.Now;
            store.ProName = txt_proname.Text;
            db.InStore.InsertOnSubmit(store);
            db.SubmitChanges();
            txt_insertcount.Text = "";
            txt_proname.Text = "";
            txt_id.Text = "";
            Bind();
        }
        /// <summary>
        /// 删除函数
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btndelete_Click(object sender, EventArgs e)
        {
            InStoreDataContext db = new InStoreDataContext();
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                HtmlInputCheckBox chk = (HtmlInputCheckBox)GridView1.Rows[i].FindControl("chk");
                if (chk.Checked)
                {
                    InStore store = db.InStore.First(p => p.Id.Equals(int.Parse(chk.Value)));
                    db.InStore.DeleteOnSubmit(store);
                    db.SubmitChanges();
                }
            }
            Bind();
        }
        /// <summary>
        /// 修改函数
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btnUpdate_Click(object sender, EventArgs e)
        {
            InStoreDataContext db = new InStoreDataContext();
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                HtmlInputCheckBox chk = (HtmlInputCheckBox)GridView1.Rows[i].FindControl("chk");
                if (chk.Checked)
                {
                    InStore store = db.InStore.First(p => p.Id.Equals(int.Parse(chk.Value)));
                    Response.Redirect("edit.aspx?id=" + chk.Value + "");
                }
            }
        }
    }
}

④，我们再添加一个Edit.aspx页面，代码如下：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Edit.aspx.cs" Inherits="LinqDemo.Edit" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <table width="60%" border="1">
            <tr>
                <td>
                    id:<asp:TextBox ID="txt_id" runat="server" Enabled="false"></asp:TextBox>
                </td>
                <td>
                    名称<asp:TextBox ID="txt_proname" runat="server"></asp:TextBox>
                </td>
                <td>
                    数量:<asp:TextBox ID="txt_insertcount" runat="server"></asp:TextBox>
                </td>
                <td>
                    <asp:Button ID="btnSummit" runat="server" OnClick="btnSummit_Click" Text="确定" />
                </td>
            </tr>
        </table>
    </div>
    </form>
</body>
</html>

Edit.aspx.cs代码如下：

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

namespace LinqDemo
{
    public partial class Edit : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            btnSummit.Attributes.Add("onclick", "javascript:return window.confirm('确定修改吗？')");
            if (!IsPostBack)
            {
                InStoreDataContext db = new InStoreDataContext();
                InStore store = db.InStore.First(p => p.Id.Equals(Request["id"].ToString()));
                txt_id.Text = store.Id.ToString();
                txt_insertcount.Text = store.InsertCount.ToString();
                txt_proname.Text = store.ProName;
            }
        }

        protected void btnSummit_Click(object sender, EventArgs e)
        {
            InStoreDataContext db = new InStoreDataContext();
            //获取当前instore表的数据行
            InStore store = db.InStore.First(p => p.Id.Equals(Request["id"].ToString()));
            //对需要修改的数据进行替换
            store.InsertCount = int.Parse(txt_insertcount.Text);
            store.ProName = txt_proname.Text;
            //最后提交修改
            db.SubmitChanges();
            Response.Redirect("List.aspx");
        }
    }
}

⑤，我们编译后，运行List.aspx页面，如图所示：

我们来添加一条数据，如下图：

点击确定后,我们发现，该数据已经提交到表InStore中了。

其它的删除，查询，修改等操作，我这里就不一一介绍了。

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标签： linq sql textbox asp server object

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