asp.net(C#)海量数据表高效率分页算法

来源：互联网发布：js 日期编辑：程序博客网时间：2024/05/21 07:04

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>");
    }
   }
}
}