c# gridview 修改问题

我想添加1个功能，能在原来的查询后的基础上，对部门这个字段可以实现修改功能，能在我现有的代码基础上添加。
前台代码：<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

        <asp:Label ID="Label1" runat="server" Text="请选择查询条件"></asp:Label>


        <asp:DropDownList ID="DropDownList1" runat="server">
            <asp:ListItem Value="name">姓名</asp:ListItem>
            <asp:ListItem Value="no">工号</asp:ListItem>
        </asp:DropDownList>

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

        <asp:Button ID="Button1" runat="server" Text="确定" onclick="Button1_Click"
            style="height: 26px" />
        <br />
                           <asp:Label
            ID="Label2" runat="server"></asp:Label>

        <br />
        <br />

    </div>
    <asp:GridView ID="GridView1" runat="server" Height="132px" Width="307px">
    </asp:GridView>
    </form>
</body>
</html>

后台代码：
using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string sqlstr;
        SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=EMPDATA;Integrated Security=True");
        con.Open();
        if (DropDownList1.Text == "name")
        {
            sqlstr = "select Emp_Name as 姓名,Emp_No as 工号,Emp_department as 部门,Emp_Tel as 电话 from guest where Emp_Name like '%" + TextBox1.Text + "%'";
        }
        else
        {
            sqlstr = "select Emp_Name as 姓名,Emp_No as 工号,Emp_department as 部门,Emp_Tel as 电话 from guest where Emp_No like '%" + TextBox1.Text + "%'";
        }
        SqlDataAdapter mySA = new SqlDataAdapter(sqlstr,con);
        DataSet ds = new DataSet();
        mySA.Fill(ds,"ss");
        GridView1.DataSource = ds;
        GridView1.DataBind();
        if (GridView1.Rows.Count == 0)
        {
            Label2.Text = "无符合数据";
        }
        else {
            Label2.Text = " ";
        }

    }
}
c# --------------------编程问答-------------------- mySA.Update(ds);
? --------------------编程问答-------------------- 能有完整的前后台代码吗？

补充：.NET技术 ,  C#