อยากทำไฮไลท์ คำที่ต้องการค้นหาค่ะ ใครเคยทำหรือมีข้อแนะนำ ขอปรึกษาหน่อยค่ะเพิ่งหัดเขียนค่ะขอบคุณล่วงหน้าเลยน่ะค่ะ

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text.RegularExpressions;
using System.Data.SqlClient;

namespace web_help_Kms
{
    public partial class GridViewSearchHeighlight : System.Web.UI.Page
    {

        static DataTable dt;
        string strConnection =
        ConfigurationManager.AppSettings["ConnectionString"];
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                dt = GetRecords();
                BindGrid();
            }

        }
        private DataTable GetRecords()
        {
            SqlConnection conn = new SqlConnection(strConnection);
            conn.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = "Select * from tb_content_topic";
            SqlDataAdapter dAdapter = new SqlDataAdapter();
            dAdapter.SelectCommand = cmd;
            DataSet objDs = new DataSet();
            dAdapter.Fill(objDs);
            return objDs.Tables[0];

        }
        private void BindGrid()
        {
            if (dt.Rows.Count > 0)
            {
                grdSearch.DataSource = dt;
                grdSearch.DataBind();
            }
        }
        private void SearchText(string strSearchText)
        {
            //DataTable dt = GetRecords();
            DataView dv = new DataView(dt);
            string SearchExpression = null;
            if (!String.IsNullOrEmpty(strSearchText))
            {
                SearchExpression =
                string.Format("{0} '%{1}%'",
                grdSearch.SortExpression, strSearchText);

            }
            dv.RowFilter = "ct_post_detail like" + SearchExpression;
            grdSearch.DataSource = dv;
            grdSearch.DataBind();

        }
        protected void grdSearch_RowCommand
            (object sender, GridViewCommandEventArgs e)
        {
            System.Threading.Thread.Sleep(500);
            if (e.CommandName == "Search")
            {
                lblMessage.Text = "";
                TextBox txtGrid =
               (TextBox)grdSearch.FooterRow.FindControl("txtSearch");
                if (txtGrid.Text != "")
                {

                    SearchText(txtGrid.Text);
                }

                else
                    lblMessage.Text = "Please enter search keyword";
            }

        }


        public string Highlight(string InputTxt)
        {
            GridViewRow gvr = grdSearch.FooterRow;
            if (gvr != null)
            {
                TextBox txtExample =
               (TextBox)grdSearch.FooterRow.FindControl("txtSearch");

                if (txtExample.Text != null)
                {
                    string strSearch = txtExample.Text;
                    //string Search_Str = txtGrid.Text.ToString();
                    // Setup the regular expression 
                    //and add the Or operator.

                    Regex RegExp =
                    new Regex(strSearch.Replace(" ", "|").Trim(),
                    RegexOptions.IgnoreCase);


                    //Highlight keywords by calling the delegate 
                    //each time a keyword is found.
                    return
            RegExp.Replace(InputTxt, new MatchEvaluator(ReplaceKeyWords));

                    // Set the RegExp to null.
                    RegExp = null;

                }
                else
                    return InputTxt;
            }
            else
            {
                return InputTxt;
            }


        }

        public string ReplaceKeyWords(Match m)
        {

            return "<span class=highlight>" + m.Value + "</span>";

        }

    }
}