asp.net(C#)海量數據表高效率分頁算法（易懂，不使用存儲過程）

2019-11-18 19:12:54

字體：大中小

來源：轉載

供稿：網友

首先創建一張表(要求ID自動編號)：
create table redheadedfile(
id int identity(1,1),
filenames nvarchar(20),
senduser nvarchar(20),
PRimary key(id)
)
然后我們寫入50萬條記錄：
declare @i int
set @i=1
while @i<=500000
begin
    insert into redheadedfile(filenames,senduser) values('我的分頁算法','陸俊銘')
    set @i=@i+1
end
GO
用Microsoft Visual Studio .NET 2003創建一張WebForm網頁(本人起名webform8.aspx)
前臺代碼片段如下(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="javaScr <meta content=" </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>頁/共

<asp:label id="LRecordCount" Runat="server" ForeColor="#ff0000"></asp:label>記錄
<asp:linkbutton id="Fistpage" Runat="server"

CommandName="0">首頁</asp:linkbutton>    <asp:linkbutton id="Prevpage" Runat="server" CommandName="prev">

上一頁</asp:linkbutton>    <asp:linkbutton id="Nextpage" Runat="server"

CommandName="next">下一頁</asp:linkbutton>    <asp:linkbutton id="Lastpage" Runat="server"

CommandName="last">尾頁</asp:linkbutton>    當前第<asp:label id="LCurrentPage" Runat="server"

ForeColor="#ff0000"></asp:label>頁    跳頁<asp:TextBox ID="gotoPage" Runat="server" Width="30px"

MaxLength="5" AutoPostBack="True"></asp:TextBox></div>
</form>
</body>
</HTML>
后臺代碼片段如下(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 的摘要說明。
/// </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;//定義每頁顯示記錄
int PageCount,RecCount,CurrentPage,Pages,JumpPage;//定義幾個保存分頁參數變量

private void Page_Load(object sender, System.EventArgs e)
{
   if(!IsPostBack)
   {
    RecCount = Calc();//通過Calc()函數獲取總記錄數
    PageCount = RecCount/PageSize + OverPage();//計算總頁數（加上OverPage()函數防止有余數造成顯示

數據不完整）

ViewState["PageCounts"] = RecCount/PageSize -

ModPage();//保存總頁參數到ViewState（減去ModPage()函數防止SQL語句執行時溢出查詢范圍，可以用存儲過程分頁算法來理解這句）
ViewState["PageIndex"] = 0;//保存一個為0的頁面索引值到ViewState
ViewState["JumpPages"] = PageCount;//保存PageCount到ViewState，跳頁時判斷用戶輸入數是否超出頁

碼范圍
    //顯示LPageCount、LRecordCount的狀態
    LPageCount.Text = PageCount.ToString();
    LRecordCount.Text = RecCount.ToString();
    //判斷跳頁文本框失效
    if(RecCount <= 20)
     gotoPage.Enabled = false;
    TDataBind();//調用數據綁定函數TDataBind()進行數據綁定運算
   }
}
        //計算余頁
public int OverPage()
{
   int pages = 0;
   if(RecCount%PageSize != 0)
    pages = 1;
   else
    pages = 0;
   return pages;
}
        //計算余頁，防止SQL語句執行時溢出查詢范圍
public int ModPage()
{
   int pages = 0;
   if(RecCount%PageSize == 0 && RecCount != 0)
    pages = 1;
   else
    pages = 0;
   return pages;
}
        /*
   *計算總記錄的靜態函數
   *本人在這里使用靜態函數的理由是：如果引用的是靜態數據或靜態函數，連接器會優化生成代碼，去掉動態重定位項（對

海量數據表分頁效果更明顯）。
   *希望大家給予意見、如有不正確的地方望指正。
*/
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;
}
        //數據庫連接語句（從Web.Config中獲?。?BR> public static SqlConnection MyCon()
{
   SqlConnection MyConnection = new SqlConnection(ConfigurationSettings.AppSettings["DSN"]);
   MyConnection.Open();
   return MyConnection;
}
        //對四個按鈕（首頁、上一頁、下一頁、尾頁）返回的CommandName值進行操作
private void Page_OnClick(object sender, CommandEventArgs e)
{
   CurrentPage = (int)ViewState["PageIndex"];//從ViewState中讀取頁碼值保存到CurrentPage變量中進行參數運

算
Pages = (int)ViewState["PageCounts"];//從ViewState中讀取總頁參數運算

   string cmd = e.CommandName;
   switch(cmd)//篩選CommandName
   {
    case "next":
     CurrentPage++;
     break;
    case "prev":
     CurrentPage--;
     break;
    case "last":
     CurrentPage = Pages;
     break;
    default:
     CurrentPage = 0;
     break;
   }
   ViewState["PageIndex"] = CurrentPage;//將運算后的CurrentPage變量再次保存至ViewState
   TDataBind();//調用數據綁定函數TDataBind()
}

private void TDataBind()
{
CurrentPage = (int)ViewState["PageIndex"];//從ViewState中讀取頁碼值保存到CurrentPage變量中進行按鈕失

效運算
   Pages = (int)ViewState["PageCounts"];//從ViewState中讀取總頁參數進行按鈕失效運算
   //判斷四個按鈕（首頁、上一頁、下一頁、尾頁）狀態
   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;
   }
            //數據綁定到DataList控件
   DataSet ds = new DataSet();
   //核心SQL語句，進行查詢運算（決定了分頁的效率:)）
   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();
   //顯示Label控件LCurrentPaget和文本框控件gotoPage狀態
   LCurrentPage.Text = (CurrentPage+1).ToString();
   gotoPage.Text = (CurrentPage+1).ToString();
   //釋放SqlDataAdapter
   MyAdapter.Dispose();
}

#region Web 窗體設計器生成的代碼
override protected void OnInit(EventArgs e)
{
   //
   // CODEGEN: 該調用是 asp.net Web 窗體設計器所必需的。
   //
   InitializeComponent();
   base.OnInit(e);
}

/// <summary>
/// 設計器支持所需的方法 - 不要使用代碼編輯器修改
/// 此方法的內容。
/// </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
        //跳頁代碼
private void gotoPage_TextChanged(object sender, System.EventArgs e)
{
   try
   {
    JumpPage = (int)ViewState["JumpPages"];//從ViewState中讀取可用頁數值保存到JumpPage變量中
    //判斷用戶輸入值是否超過可用頁數范圍值
    if(Int32.Parse(gotoPage.Text) > JumpPage || Int32.Parse(gotoPage.Text) <= 0)

Response.Write("<script>alert('頁碼范圍越界！');location.href='WebForm8.aspx'</script>");
    else
    {
     int InputPage = Int32.Parse(gotoPage.Text.ToString()) - 1;//轉換用戶輸入值保存在int型

InputPage變量中
     ViewState["PageIndex"] = InputPage;//寫入InputPage值到ViewState["PageIndex"]中
     TDataBind();//調用數據綁定函數TDataBind()再次進行數據綁定運算
    }
   }
      //捕獲由用戶輸入不正確數據類型時造成的異常
   catch(Exception exp)
   {
    Response.Write("<script>alert('"+exp.Message+"');location.href='WebForm8.aspx'</script>");
   }
}
}
}

大家來試試，效率是不是高了很多？

如有不妥望大家來指正

上一篇：在Asp.net中為圖像加入版權信息

下一篇：靈活正確的實現.NET插件機制