asp.net(C#)海量数据表高效率分页算法(易懂,不使用存储过程)

3/29/2006来源:ASP.NET技巧人气:12706

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>&nbsp;&nbsp;&nbsp;&nbsp;<asp:linkbutton id="Prevpage" Runat="server" CommandName="prev">

上一页</asp:linkbutton>&nbsp;&nbsp;&nbsp;&nbsp;<asp:linkbutton id="Nextpage" Runat="server"

CommandName="next">下一页</asp:linkbutton>&nbsp;&nbsp;&nbsp;&nbsp;<asp:linkbutton id="Lastpage" Runat="server"

CommandName="last">尾页</asp:linkbutton>&nbsp;&nbsp;&nbsp;&nbsp;当前第<asp:label id="LCurrentPage" Runat="server"

ForeColor="#ff0000"></asp:label>页&nbsp;&nbsp;&nbsp;&nbsp;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


            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>");
   }
  }
 }
}

大家来试试,效率是不是高了很多?