i am doing using Gridview uisng asp.net csharp code

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.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 

{

    SqlConnection con = new SqlConnection("Server=(local);initial catalog=Master;Trusted_Connection=True");

    protected void Page_Load(object sender, EventArgs e)

    {

        

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        SqlDataAdapter da = new SqlDataAdapter("SELECT CategoryID,CategoryName from quest", con);

        DataTable dt = new DataTable();

        da.Fill(dt);

        DataRow dr = dt.NewRow();

        dt.Rows.InsertAt(dr, 0);

        GridView1.EditIndex = 0;

        GridView1.DataSource = dt;

        GridView1.DataBind();

    }

    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)

    {

    }

    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)

    {

         if (((LinkButton)GridView1.Rows[0].Cells[0].Controls[0]).Text == "Insert")

               {

        SqlCommand cmd = new SqlCommand();

        cmd.CommandText = "Insert into quest (CategoryName) values(CategoryName)";

        cmd.Parameters.Add("CategoryName", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[0].Cells[2].Controls[0]).Text;

        cmd.Connection = con;

        con.Open();

        cmd.ExecuteNonQuery();

        con.Close();

    }

    else

         {

          SqlCommand cmd = new SqlCommand();

             cmd.CommandText = "Update quest SET CategoryName=@CategoryName where CategoryID=@CategoryID";

             cmd.Parameters.Add("@CategoryName",SqlDbType.VarChar).Value=((TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text;

             cmd.Parameters.Add("@CategoryID",SqlDbType.Int).Value= Convert.ToInt32(GridView1.Rows[e.RowIndex].Cells[1].Text;

             cmd.Connection = con;

             con.Open();

             cmd.ExecuteNonQuery();

             con.Close();

         }

    }

    }

}