asp.net(C#)海量数据表高效率分页算法

asp.net(C#)海量数据表高效率分页算法

首先创建一张表(要求ID自动编号)：

create table redheadedfile
(
    id          int identity(1,1),
    filenames   nvarchar(20),
    senduser    nvarchar(20),
    primary key(id)
)

然后我们写入50万条记录：

declare @i int
set @i=1
while @i<=500000
begin
    insert into redheadedfile(filenames,senduser) values('我的分页算法','陆俊铭')
    set @i=@i+1
end
GO

用Microsoft Visual Studio .net 2003创建一张WebForm网页(本人起名webform8.ASPx)
前台代码片段如下(webform8.aspx)：

<%@ Page language="C#" Codebehind="WebForm8.aspx.cs" AutoEventWireup="false" Inherits="WebApplication6.WebForm8" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
  <title>WebForm8</title>
  <meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR">
  <meta content="C#" name="CODE_LANGUAGE">
  <meta content="JavaScript" name="vs_defaultClientScript">
  <meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
</HEAD>
<body MS_POSITIONING="GridLayout">
  <form id="Form1" method="post" runat="server">
   <asp:datalist id="datalist1" AlternatingItemStyle-BackColor="#f3f3f3" Width="100%" CellSpacing="0"
    CellPadding="0" Runat="server">
    <ItemTemplate>
     <table width="100%" border="0" cellspacing="0" cellpadding="0">
      <tr>
       <td width="30%" align="center"><%#DataBinder.Eval(Container.DataItem,"filenames")%></td>
       <td width="30%" align="center"><%#DataBinder.Eval(Container.DataItem,"senduser")%></td>
       <td width="30%" align="center"><%#DataBinder.Eval(Container.DataItem,"id")%></td>
      </tr>
     </table>
    </ItemTemplate>
   </asp:datalist>
   <div align="center">共<asp:label id="LPageCount" Runat="server" ForeColor="#ff0000"></asp:label>页/共
         <asp:label id="LRecordCount" Runat="server" ForeColor="#ff0000"></asp:label>记录
         <asp:linkbutton id="Fistpage" Runat="server" CommandName="0">首页</asp:linkbutton>    

         <asp:linkbutton id="Prevpage" Runat="server" CommandName="prev">上一页</asp:linkbutton>    

         <asp:linkbutton id="Nextpage" Runat="server" CommandName="next">下一页</asp:linkbutton>    

         <asp:linkbutton id="Lastpage" Runat="server" CommandName="last">尾页</asp:linkbutton>    当前第

         <asp:label id="LCurrentPage" Runat="server" ForeColor="#ff0000"></asp:label>页    跳页

         <asp:TextBox ID="gotoPage" Runat="server" Width="30px" MaxLength="5" AutoPostBack="True"></asp:TextBox>

   </div>
  </form>
</body>
</HTML>

后台代码片段如下(webform8.aspx.cs)

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Configuration;

namespace WebApplication6
{
    /// <summary>
    /// WebForm8 的摘要说明。
    /// </summary>
    public class WebForm8 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.LinkButton Fistpage;
        protected System.Web.UI.WebControls.LinkButton Prevpage;
        protected System.Web.UI.WebControls.LinkButton Nextpage;
        protected System.Web.UI.WebControls.LinkButton Lastpage;
        protected System.Web.UI.WebControls.DataList datalist1;
        protected System.Web.UI.WebControls.DropDownList mydroplist;
        protected System.Web.UI.WebControls.Label LPageCount;
        protected System.Web.UI.WebControls.Label LRecordCount;
        protected System.Web.UI.WebControls.Label LCurrentPage;
        protected System.Web.UI.WebControls.TextBox gotoPage;
        const int PageSize = 20;//定义每页显示记录
        int PageCount, RecCount, CurrentPage, Pages, JumpPage;//定义几个保存分页参数变量

        private void Page_Load(object sender, System.EventArgs e)
        {
            if (!IsPostBack)
            {
                RecCount = Calc();//通过Calc()函数获取总记录数
                PageCount = RecCount / PageSize + OvERPage();//计算总页数（加上OverPage()函数防止有余数造成显示数据不完整）

                ViewState["PageCounts"] = RecCount / PageSize - ModPage();//保存总页参数到ViewState（减去ModPage()函数防止SQL语句执行时溢出查询范围，可以用存储过程分页算法来理解这句）
                ViewState["PageIndex"] = 0;//保存一个为0的页面索引值到ViewState
                ViewState["JumpPages"] = PageCount;//保存PageCount到ViewState，跳页时判断用户输入数是否超出页码范围
                //显示LPageCount、LRecordCount的状态
                LPageCount.Text = PageCount.ToString();
                LRecordCount.Text = RecCount.ToString();
                //判断跳页文本框失效
                if (RecCount <= 20)
                    gotoPage.Enabled = false;
                TDataBind();//调用数据绑定函数TDataBind()进行数据绑定运算
            }
        }
        //计算余页
        public int OverPage()
        {
            int pages = 0;
            if (RecCount % PageSize != 0)
                pages = 1;
            else
                pages = 0;
            return pages;
        }
        //计算余页，防止SQL语句执行时溢出查询范围
        public int ModPage()
        {
            int pages = 0;
            if (RecCount % PageSize == 0 && RecCount != 0)
                pages = 1;
            else
                pages = 0;
            return pages;
        }
        /*
   *计算总记录的静态函数
   *本人在这里使用静态函数的理由是：如果引用的是静态数据或静态函数，连接器会优化生成代码，去掉动态重定位项（对海量数据表分页效果更明显）。
   *希望大家给予意见、如有不正确的地方望指正。 */
        public static int Calc()
        {
            int RecordCount = 0;
            SqlCommand MyCmd = new SqlCommand("select count(*) as co from redheadedfile", MyCon());
            SqlDataReader dr = MyCmd.ExecuteReader();
            if (dr.Read())
                RecordCount = Int32.Parse(dr["co"].ToString());
            MyCmd.Connection.Close();
            return RecordCount;
        }
        //数据库连接语句（从Web.Config中获取）
        public static SqlConnection MyCon()
        {
            SqlConnection MyConnection = new SqlConnection(ConfigurationSettings.AppSettings["DSN"]);
            MyConnection.Open();
            return MyConnection;
        }
        //对四个按钮（首页、上一页、下一页、尾页）返回的CommandName值进行操作
        private void Page_OnClick(object sender, CommandEventArgs e)
        {
            CurrentPage = (int)ViewState["PageIndex"];//从ViewState中读取页码值保存到CurrentPage变量中进行参数运算
            Pages = (int)ViewState["PageCounts"];//从ViewState中读取总页参数运算

            string cmd = e.CommandName;
            switch (cmd)//筛选CommandName
            {
                case "next":
                    CurrentPage++;
                    break;
                case "prev":
                    CurrentPage--;
                    break;
                case "last":
                    CurrentPage = Pages;
                    break;
                default:
                    CurrentPage = 0;
                    break;
            }
            ViewState["PageIndex"] = CurrentPage;//将运算后的CurrentPage变量再次保存至ViewState
            TDataBind();//调用数据绑定函数TDataBind()
        }

        private void TDataBind()
        {
            CurrentPage = (int)ViewState["PageIndex"];//从ViewState中读取页码值保存到CurrentPage变量中进行按钮失效运算
            Pages = (int)ViewState["PageCounts"];//从ViewState中读取总页参数进行按钮失效运算
            //判断四个按钮（首页、上一页、下一页、尾页）状态
            if (CurrentPage + 1 > 1)
            {
                Fistpage.Enabled = true;
                Prevpage.Enabled = true;
            }
            else
            {
                Fistpage.Enabled = false;
                Prevpage.Enabled = false;
            }
            if (CurrentPage == Pages)
            {
                Nextpage.Enabled = false;
                Lastpage.Enabled = false;
            }
            else
            {
                Nextpage.Enabled = true;
                Lastpage.Enabled = true;
            }
            //数据绑定到DataList控件
            DataSet ds = new DataSet();
            //核心SQL语句，进行查询运算（决定了分页的效率:)）
            SqlDataAdapter MyAdapter = new SqlDataAdapter("Select Top " + PageSize + " * from redheadedfile where id not in(select top " + PageSize * CurrentPage + " id from redheadedfile order by id asc) order by id asc", MyCon());
            MyAdapter.Fill(ds, "news");
            datalist1.DataSource = ds.Tables["news"].DefaultView;
            datalist1.DataBind();
            //显示Label控件LCurrentPaget和文本框控件gotoPage状态
            LCurrentPage.Text = (CurrentPage + 1).ToString();
            gotoPage.Text = (CurrentPage + 1).ToString();
            //释放SqlDataAdapter
            MyAdapter.Dispose();
        }

        #region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }

        /// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            this.Fistpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);
            this.Prevpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);
            this.Nextpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);
            this.Lastpage.Command += new System.Web.UI.WebControls.CommandEventHandler(this.Page_OnClick);
            this.gotoPage.TextChanged += new System.EventHandler(this.gotoPage_TextChanged);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion
        //跳页代码
        private void gotoPage_TextChanged(object sender, System.EventArgs e)
        {
            try
            {
                JumpPage = (int)ViewState["JumpPages"];//从ViewState中读取可用页数值保存到JumpPage变量中
                //判断用户输入值是否超过可用页数范围值
                if (Int32.Parse(gotoPage.Text) > JumpPage || Int32.Parse(gotoPage.Text) <= 0)
                    Response.Write("<script>alert('页码范围越界！');location.href='WebForm8.aspx'</script>");
                else
                {
                    int InputPage = Int32.Parse(gotoPage.Text.ToString()) - 1;//转换用户输入值保存在int型InputPage变量中
                    ViewState["PageIndex"] = InputPage;//写入InputPage值到ViewState["PageIndex"]中
                    TDataBind();//调用数据绑定函数TDataBind()再次进行数据绑定运算
                }
            }
            //捕获由用户输入不正确数据类型时造成的异常
            catch (Exception exp)
            {
                Response.Write("<script>alert('" + exp.Message + "');location.href='WebForm8.aspx'</script>");
            }
        }
    }
}
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原文地址：https://www.cnblogs.com/purplefox2008/p/1777851.html