Add Sort Functionality To GridView Using C#

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C#

ASP.NET

SQL

I have an existing search page that will search records in a SQL DB using a stored procedure. Search results are posted to a GridView on the same page. I would like to include sort functionality because a search can return multiple records, but I'm not sure how to add this to the existing C#. The code for the GridView (as well as text box and search button) is currently:

        <p>Search for someone by name, email address, or employee ID</p>
<!-- Panel sets Button1 as default, to click on Enter key -->    
    <asp:Panel ID="panSearch" runat="server" DefaultButton="Button1">
    <asp:TextBox ID="TextBox1" runat="server" MaxLength="100"></asp:TextBox>
    </asp:Panel>
    <br />
    <asp:Button ID="Button1" runat="server" Text="Search" OnClick="Button1_Click" /><br />
    <br />

<!-- redirect to new URL on Select achieved through asp:hyperlinkfield -->
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" Width="90%" AlternatingRowStyle-BackColor="#E2E2E2">
        <Columns>
            <asp:HyperLinkField DataNavigateUrlFields="PK" DataNavigateUrlFormatString="PeopleSearch2.aspx?PK={0}" Text="Select"></asp:HyperLinkField>
            <asp:BoundField DataField="FirstName" HeaderText="First" SortExpression="FirstName"></asp:BoundField>
            <asp:BoundField DataField="LastName" HeaderText="Last" SortExpression="LastName"></asp:BoundField>
            <asp:BoundField DataField="Email" HeaderText="Email" SortExpression="Email"></asp:BoundField>
            <asp:BoundField DataField="Manager" HeaderText="Manager" SortExpression="Manager"></asp:BoundField>
            <asp:BoundField DataField="EmpStatus" HeaderText="Status" SortExpression="EmpStatus"></asp:BoundField>
                 

        </Columns>
    </asp:GridView>

My guess is that for the GridView, I would only need to add AllowSorting="true" and OnSorting="GridView1_Sorting" but then I'll need to add GridView1_Sorting to the code behind and possibly modify my existing C#. I don't want to lose any current functionality. The C# code is currently:

using System;
using System.Data;
using System.Configuration;
using System.Collections.Generic;
using System.Linq;
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.Data.SqlClient;

namespace Max.Security
{
    public partial class PeopleSearch1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            TextBox1.Focus();  // this sets the cursor to the textbox on page load
            {
                if (Request.QueryString["searchString"] != null)
                {
                    DisplaySearchResults(Request.QueryString["searchString"]);
                }
            }
        }

        public void DisplaySearchResults(string strSearch)
        {
            SqlCommand cmd = new SqlCommand("dbo.aspPeopleSearch", new SqlConnection(ConfigurationManager.AppSettings["ConnString"]));
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@SearchString", strSearch);
            cmd.Connection.Open();

            GridView1.DataSource = cmd.ExecuteReader();
            GridView1.DataBind();

            cmd.Connection.Close();
            cmd.Connection.Dispose();
        }


        protected void Button1_Click(object sender, EventArgs e)  // this allows the Enter key to fire button1
        {
            Response.Redirect("PeopleSearch1.aspx?searchString=" + Server.UrlEncode(TextBox1.Text)); 
        }



    }
}