สอบถามการ paging Gridview Asp.net รบกวนผู้รู้ช่วยแนะนำด้วยครับ

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="StaffDirectory_Default" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
    <script type="text/javascript">
        function autocomplete_Populated(sender, e) {
            if (sender._currentPrefix != null) {

                var list = sender.get_completionList();
                var search = sender._currentPrefix.replace(" ", "").toLowerCase();

                for (var i = 0; i < list.childNodes.length; i++) {
                    var text = list.childNodes[i].innerHTML;
                    var index = text.toLowerCase().indexOf(search);

                    if (index != -1) {
                        var value = text.substring(0, index);
                        value += '<span style="color: black;">';
                        value += text.substr(index, search.length);
                        value += '</span>';
                        value += text.substring(index + search.length);

                        list.childNodes[i].innerHTML = value;
                    }
                }
            }
        }

        function autocomplete_Selected(sender, e) {

            var SelectedText;
            // Check for IE - should really check for the availabbility of the property... if(e._item.innerText)
            if (document.all)
                SelectedText = e._item.innerText;
            else
                SelectedText = e._item.textContent;
            // Set the value of the textbox
            sender.get_element().value = SelectedText;

            // Get the value selected
            SelectedValue = e.get_value();
        }   
    </script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <div class="Staff">
        <h1>ระบบค้นหาบุคคลากร</h1><br />
        <asp:TextBox ID="TextBoxStaff" Width="400px" runat="server" autocomplete="off"></asp:TextBox>
        <ajaxToolkit:AutoCompleteExtender ID="TextBoxStaff_AutoCompleteExtender" BehaviorID="AutoCompleteEx" runat="server"
            TargetControlID="TextBoxStaff"
            ServicePath="~/AutoComplete.asmx"
            ServiceMethod="GetStaffList"
            CompletionInterval="100"
            CompletionSetCount="12"
            DelimiterCharacters=""
            Enabled="true"
            EnableCaching="true"
            MinimumPrefixLength="1"
            CompletionListCssClass="autocomplete_completionListElement"
            CompletionListItemCssClass="autocomplete_listItem"
            CompletionListHighlightedItemCssClass="autocomplete_highlightedListItem"
            OnClientPopulated="autocomplete_Populated"
            OnClientItemSelected="autocomplete_Selected"
            ShowOnlyCurrentWordInCompletionListItem="true">
        </ajaxToolkit:AutoCompleteExtender>
        <asp:Button ID="ButtonSearch" runat="server" ValidationGroup="staff" Text="ค้นหา" OnClick="ButtonSearch_Click" />
        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" ControlToValidate="TextBoxStaff" CssClass="failureNotification" runat="server" ErrorMessage="*" ValidationGroup="staff"></asp:RequiredFieldValidator>
        <asp:UpdateProgress ID="UpdateProgress1" DynamicLayout="false" runat="server">
            <ProgressTemplate>
                <asp:Image ID="Image1" ImageUrl="~/images/loading.gif" runat="server" />
            </ProgressTemplate>
        </asp:UpdateProgress>

        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="ButtonSearch" EventName="Click" />
            </Triggers>
            <ContentTemplate>
            <asp:GridView ID="GridView1" runat="server" AllowPaging="True" PageSize="25"
                OnRowDataBound="GridView1_RowDataBound" OnPageIndexChanging="GridView1_PageIndexChanging" OnRowCommand="GridView1_RowCommand">
                <Columns>
                    <asp:TemplateField HeaderText=" ">
                        <EditItemTemplate>
                            <asp:TextBox ID="TextBoxUserID" runat="server"></asp:TextBox>
                        </EditItemTemplate>
                        <ItemTemplate>
                            <asp:ImageButton ID="ImageButtonDetail" runat="server" CausesValidation="false" ToolTip="แสดงรายละเอียด"
                                ImageUrl="~/images/details.png" CommandName="ShowDetail" CommandArgument='<%# Bind("StaffID") %>' />
                        </ItemTemplate>
                        <HeaderStyle Width="3%" />
                        <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" />
                    </asp:TemplateField>
                    <asp:BoundField HeaderText="#">
                    <HeaderStyle HorizontalAlign="Center" Width="3%" />
                    <ItemStyle HorizontalAlign="Right" VerticalAlign="Middle" />
                    </asp:BoundField>
                    <asp:BoundField HeaderText="ชื่อ" DataField="StaffName">
                    <HeaderStyle HorizontalAlign="Center" Width="25%" />
                    <ItemStyle HorizontalAlign="Left" VerticalAlign="Middle" />
                    </asp:BoundField>
                    <asp:BoundField HeaderText="ตำแหน่ง" DataField="PositionName">
                    <HeaderStyle HorizontalAlign="Center" Width="29%" />
                    <ItemStyle HorizontalAlign="Left" VerticalAlign="Middle" />
                    </asp:BoundField>                
                    <asp:BoundField HeaderText="หน่วยงาน" DataField="SectionName">
                    <HeaderStyle HorizontalAlign="Center" Width="30%" />
                    <ItemStyle HorizontalAlign="Left" VerticalAlign="Middle" />
                    </asp:BoundField>
                    <asp:BoundField HeaderText="โทรศัพท์" DataField="IpPhone">
                    <HeaderStyle HorizontalAlign="Center" Width="10%" />
                    <ItemStyle HorizontalAlign="Right" VerticalAlign="Middle" />
                    </asp:BoundField>
                </Columns>
            </asp:GridView> 
            
            <asp:Button ID="ButtonHidden" runat="server" Text="Button" style="display: none;" />
            <ajaxToolkit:ModalPopupExtender runat="server" ID="ModalPopupExtender1"
                TargetControlID="ButtonHidden" PopupControlID="PanelPopup" CancelControlID="ImageButtonClose"
                BackgroundCssClass="modalBackground" DropShadow="True"
                RepositionMode="RepositionOnWindowScroll">
            </ajaxToolkit:ModalPopupExtender>
            <asp:Panel ID="PanelPopup" CssClass="modalPopup" style="display: none; padding: 0px;" runat="server">
                <asp:Panel ID="PanelClose" CssClass="close" runat="server">
                    <asp:ImageButton ID="ImageButtonClose" ImageUrl="~/images/close.png" ToolTip="Close" runat="server" />
                </asp:Panel>
                <asp:Panel ID="PanelFrame" CssClass="Frame" runat="server">
                    <asp:Panel ID="PanelDetail" CssClass="Detail" runat="server">
                        <fieldset class="dataDetail">
                            <legend>ข้อมูลเจ้าหน้าที่:</legend>    
                            <table class="tableDetail">
                                <tr>
                                    <td style="width: 20%;">ชื่อ:</td>
                                    <td style="width: 60%;">
                                        <asp:Label ID="LabelName" runat="server" Font-Bold="true" Text="Label"></asp:Label>
                                    </td>
                                    <td style="width: 20%; text-align: right; vertical-align: top;" rowspan="3">
                                        <asp:Image ID="ImageAvatar" Width="100" Height="125" BorderWidth="1px" BorderStyle="Solid" BorderColor="#cccccc" runat="server" ImageUrl="~/images/male-icon-120x150.jpg" />
                                    </td>
                                </tr>
                                <tr>
                                    <td>ตำแหน่ง:</td>
                                    <td>
                                        <asp:Label ID="LabelPosition" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td style="vertical-align: top;">สังกัด:</td>
                                    <td>
                                        <asp:BulletedList ID="BulletedListSection" CssClass="Section" runat="server">
                                        </asp:BulletedList>
                                    </td>
                                </tr>
                                <tr>
                                    <td>ผู้บังคับบัญชา:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelBoss" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td style="vertical-align: top;">สถานที่ทำงาน:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelAddress" runat="server" style="line-height: 24px;" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td>จังหวัด:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelProvince" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td style="vertical-align: top;">โทรศัพท์:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelPhone" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td style="vertical-align: top;">โทรศัพท์เคลื่อนที่:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelMobile" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td style="vertical-align: top;">โทรสาร:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelFax" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td style="vertical-align: top;">อีเมล:</td>
                                    <td colspan="2">
                                        <asp:Label ID="LabelEmail" runat="server" Text="Label"></asp:Label>
                                    </td>
                                </tr>
                            </table>                
                        </fieldset>
                    </asp:Panel>
                </asp:Panel>               
            </asp:Panel>   
                   
            </ContentTemplate>
        </asp:UpdatePanel>
    </div>
</asp:Content>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Data;

public partial class StaffDirectory_Default : System.Web.UI.Page
{
    protected void Page_PreInit(object sender, EventArgs e)
    {
        if (Request.Cookies["userSetting"] == null)
            this.Page.Theme = "Default";
        else
            this.Page.Theme = Request.Cookies["userSetting"]["Theme"].ToString();
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            GridView1.DataSource = new DataTable();
            GridView1.DataBind();        
        }
    }

    protected void ButtonSearch_Click(object sender, EventArgs e)
    {
        GridView1.DataSource = GetStaff(TextBoxStaff.Text.Replace("[", string.Empty).Replace("]", string.Empty).Replace("#", string.Empty));
        GridView1.DataBind();
    }

    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        GridView gv = (GridView)sender;

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            e.Row.Cells[2].ToolTip = e.Row.Cells[2].Text;
            e.Row.Cells[3].ToolTip = e.Row.Cells[3].Text;
            e.Row.Cells[4].ToolTip = e.Row.Cells[4].Text;
            e.Row.Cells[5].ToolTip = e.Row.Cells[5].Text;

            e.Row.Cells[1].Text = string.Format("{0}.", ((e.Row.RowIndex + 1) + (gv.PageIndex * gv.PageSize)).ToString());
            e.Row.Cells[2].Text = (e.Row.Cells[2].Text.Trim().Length > 25) ? string.Format("{0}...", e.Row.Cells[2].Text.Substring(0, 25)) : e.Row.Cells[2].Text;
            e.Row.Cells[3].Text = (e.Row.Cells[3].Text.Trim().Length > 25) ? string.Format("{0}...", e.Row.Cells[3].Text.Substring(0, 25)) : e.Row.Cells[3].Text;
            e.Row.Cells[4].Text = (e.Row.Cells[4].Text.Trim().Length > 25) ? string.Format("{0}...", e.Row.Cells[4].Text.Substring(0, 25)) : e.Row.Cells[4].Text;
            e.Row.Cells[5].Text = (e.Row.Cells[5].Text.Trim().Length > 6) ? string.Format("{0}...", e.Row.Cells[5].Text.Substring(0, 6)) : e.Row.Cells[5].Text;
        }
    }

    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        GridView1.DataSource = GetStaff(TextBoxStaff.Text.Replace("[", string.Empty).Replace("]", string.Empty).Replace("#", string.Empty));
        GridView1.PageIndex = e.NewPageIndex;
        GridView1.DataBind();
    }

    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "ShowDetail")
        {
            DataRow Staff = GetStaffDetail(Convert.ToInt32(e.CommandArgument)).Rows[0];

            ImageAvatar.ImageUrl = (!string.IsNullOrEmpty(Staff["ImagePath"].ToString())) ? Staff["ImagePath"].ToString() : ImageDefault(Convert.ToInt32(Staff["PrefixID"]));
            LabelName.Text = Staff["StaffName"].ToString();
            LabelPosition.Text = Staff["PositionName"].ToString();
            BulletedListSection.DataSource = GetSection(Staff["SectionName"].ToString(), Staff["ParentCode"].ToString());
            BulletedListSection.DataBind();
            LabelBoss.Text = (!string.IsNullOrEmpty(Staff["BossID"].ToString())) ? GetBossName(Convert.ToInt32(Staff["BossID"])) : "-";
            LabelAddress.Text = (!string.IsNullOrEmpty(Staff["Address"].ToString())) ? Staff["Address"].ToString() : "-";
            LabelProvince.Text = (!string.IsNullOrEmpty(Staff["Province"].ToString())) ? Staff["Province"].ToString() : "-";
            LabelPhone.Text = (!string.IsNullOrEmpty(Staff["IpPhone"].ToString())) ? Staff["IpPhone"].ToString() : "-";
            LabelMobile.Text = (!string.IsNullOrEmpty(Staff["Mobile"].ToString())) ? Staff["Mobile"].ToString() : "-";
            LabelFax.Text = (!string.IsNullOrEmpty(Staff["Fax"].ToString())) ? Staff["Fax"].ToString() : "-";
            LabelEmail.Text = (!string.IsNullOrEmpty(Staff["Email"].ToString())) ? Staff["Email"].ToString() : "-";

            ModalPopupExtender1.Show();
        }
    }

    protected DataTable GetStaffDetail(int StaffID)
    {
        Intranet2012DataContext intranet2012 = new Intranet2012DataContext();

        var staff = from s in intranet2012.Staff
                    join pf in intranet2012.Prefix on s.PrefixID equals pf.ID
                    join p in intranet2012.Position on s.PositionID equals p.ID
                    join c in intranet2012.CommandLine on s.CommandCode equals c.CommandCode
                    join st in intranet2012.Section on s.SectionCode equals st.SectionCode
                    join pv in intranet2012.Province on s.ProvinceID equals pv.ID into pvLeftJoin
                    from pv in pvLeftJoin.DefaultIfEmpty()
                    where s.ID == StaffID
                    select new
                    {
                        ImagePath = s.ImagePath,
                        PrefixID = s.PrefixID,
                        StaffName = string.Format("{0} {1} {2}", pf.PrefixName, s.Name, s.LastName),
                        Address = s.Address,
                        Province = pv.ProvinceName,
                        PositionName = p.PositionName,
                        BossID = c.StaffID,
                        SectionName = st.SectionName,
                        ParentCode = st.ParentCode,
                        IpPhone = GetIpPhone(s.ID, 1),
                        Mobile = GetIpPhone(s.ID, 2),
                        Fax = GetIpPhone(s.ID, 3),
                        Email = s.Email
                    };

        return Intranet2012Datebase.LINQToDataTable(staff);
    }

    protected string GetBossName(int BossID)
    { 
        Intranet2012DataContext intranet2012 = new Intranet2012DataContext();

        string boss = (from s in intranet2012.Staff
                       join pf in intranet2012.Prefix on s.PrefixID equals pf.ID
                       join p in intranet2012.Position on s.PositionID equals p.ID
                       where s.ID == BossID
                       orderby s.Name
                       select new
                       {
                           BossName = string.Format("{0} {1} {2} [{3}]", pf.PrefixName, s.Name, s.LastName, p.PositionName)
                       }).Select(b => b.BossName).First();

        return boss;
    }

    protected string[] GetSection(string SectionName, string ParentCode)
    {
        Intranet2012DataContext intranet2012 = new Intranet2012DataContext();

        List<string> section = new List<string>();
        string parentCode = ParentCode;
        if (SectionName != "ไม่ระบุ") section.Add(SectionName);

        while (Convert.ToInt32(parentCode) > 0)
        {
            TableSection aSection = (from s in intranet2012.Section
                                     where s.SectionCode == parentCode
                                     select s).First();

            if (aSection.SectionName != "ไม่ระบุ") section.Add(aSection.SectionName);
            parentCode = aSection.ParentCode;
        }

        return section.ToArray();
    }

    protected DataTable GetStaff(string prefixText)
    {
        Intranet2012DataContext intranet2012 = new Intranet2012DataContext();

        string keyWord = prefixText.Trim().Replace(" ", string.Empty);

        var staff = from s in intranet2012.Staff
                    join p in intranet2012.Position on s.PositionID equals p.ID
                    join ss in (from sss in intranet2012.Section where sss.SectionCode.EndsWith("00") select sss) on s.SectionCode.Substring(0, s.SectionCode.Length - 2) equals ss.SectionCode.Substring(0, ss.SectionCode.Length - 2)
                    join pv in intranet2012.Province on s.ProvinceID equals pv.ID into pvLeftJoin
                    from pv in pvLeftJoin.DefaultIfEmpty()
                    where s.Status == true && ((s.Name.Trim().Replace(" ", string.Empty) + s.LastName.Trim().Replace(" ", string.Empty)).StartsWith(keyWord) ||
                    s.LastName.Trim().Replace(" ", string.Empty).StartsWith(keyWord) ||
                    ss.SectionName.Trim().StartsWith(keyWord) || ss.SectionShortName.Trim().StartsWith(keyWord) || s.Email.Trim().StartsWith(keyWord) ||
                    p.PositionName.Trim().StartsWith(keyWord) || pv.ProvinceName.Trim().StartsWith(keyWord)) ||
                    (from pt in intranet2012.Phone where pt.StaffID == s.ID && pt.TypeID == 1 && pt.Number.Trim().StartsWith(keyWord) select pt).Count() > 0 ||
                    (from pt in intranet2012.Phone where pt.StaffID == s.ID && pt.TypeID == 2 && pt.Number.Trim().StartsWith(keyWord) select pt).Count() > 0 ||
                    (from pt in intranet2012.Phone where pt.StaffID == s.ID && pt.TypeID == 3 && pt.Number.Trim().StartsWith(keyWord) select pt).Count() > 0
                    orderby ss.SectionCode, s.Name ascending
                    select new
                    {
                        StaffID = s.ID,
                        StaffName = string.Format("{0} {1}", s.Name.Trim(), s.LastName.Trim()),
                        PositionName = p.PositionName,
                        SectionName = ss.SectionName,
                        IpPhone = GetIpPhone(s.ID, 1)
                    };

        return Intranet2012Datebase.LINQToDataTable(staff);
    }

    protected string GetIpPhone(int StaffID, int TypeID)
    {
        Intranet2012DataContext intranet2012 = new Intranet2012DataContext();

        string number = string.Empty;

        (from p in intranet2012.Phone
         where p.TypeID == TypeID && p.StaffID == StaffID
         select p).ToList().ForEach(p => number += string.Format("{0}, ", NumberFormat(p.Number)));

        return (number.Length > 0) ? number.Substring(0, number.Length - 2) : number;
    }

    protected string NumberFormat(string Number)
    {
        string result = string.Empty;

        if (Number.Substring(0, 2) == "02")
        {
            result = string.Format("{0} {1} {2}", Number.Substring(0, 1), Number.Substring(1, 4), Number.Substring(5));
        }
        else if (Number.Substring(0, 2) == "08")
        {
            result = string.Format("{0} {1} {2}", Number.Substring(0, 2), Number.Substring(2, 4), Number.Substring(6));
        }
        else
        {
             result = Number;
        }

        return result;
    }

    protected string ImageDefault(int PrefixID)
    {
        string imageDefalut;

        switch (PrefixID)
        {
            case 2:
            case 3:
            case 8:
                imageDefalut = "~/images/female-icon-120x150.jpg";
                break;
            default:
                imageDefalut = "~/images/male-icon-120x150.jpg";
                break;
        }

        return imageDefalut;
    }
}