Deleting rows in grid

Hi,
   i am trying the code for deleting records in the gridview, but after selecting ckeckbox and clicking on delete button all the rows data is getting deleted, i wanted to delete only check box marked row data. i am not getting what mistake i have did. my sample code is shown below.
  my .aspx code is


<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" Debug="true"%>





   


   

   

   
DataKeyNames="cat_id" ForeColor="#333333" GridLines="None" OnRowCancelingEdit="GridView1_RowCancelingEdit"

OnRowEditing="GridView1_RowEditing" OnRowUpdating="GridView1_RowUpdating">







                   

                       

                   

                   

                       

                   

               


























                    onclick="Button1_Click" />
                                               
           
   

   

and my .aspx.cs code is


using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

using System.Collections.Specialized;

using System.Text;
using System.Collections;

public partial class Default3 : System.Web.UI.Page
{
     SqlConnection con = new SqlConnection();

    SqlCommand cmd = new SqlCommand();

    string connectionString = "Data Source=hobvision07;Initial Catalog=master; user id=sa;password=hobvision";

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindData();
           
            btnDelete.Attributes.Add("onclick",
         "return confirm('Are you sure you want to delete selected item(s) ?');");
        }

    }
    private void BindData()
    {
        SqlConnection con = new SqlConnection("Data source=hobvision07; initial catalog=master; user id=sa; password=hobvision");

        SqlDataAdapter da = new SqlDataAdapter("SELECT cat_id, cat_name,location,date FROM quest_categories", con);
        DataTable dt = new DataTable();

        da.Fill(dt);

        GridView1.DataSource = dt;

        GridView1.DataBind();

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection("Data source=hobvision07; initial catalog=master; user id=sa; password=hobvision");

        SqlDataAdapter da = new SqlDataAdapter("SELECT cat_id, cat_name,location,date FROM quest_categories", con);
        DataTable dt = new DataTable();

        da.Fill(dt);

        // Here we'll add a blank row to the returned DataTable
        DataRow dr = dt.NewRow();

        dt.Rows.InsertAt(dr, 0);

        //Creating the first row of GridView to be Editable

        GridView1.EditIndex = 0;

        GridView1.DataSource = dt;

        GridView1.DataBind();

        //Changing the Text for Inserting a New Record
        ((LinkButton)GridView1.Rows[0].Cells[1].Controls[0]).Text = "Insert";
    }
    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {

        GridView1.EditIndex = e.NewEditIndex;

        BindData();

    }
    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {

        GridView1.EditIndex = -1;

        BindData();

    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        if (((LinkButton)GridView1.Rows[0].Cells[1].Controls[0]).Text == "Insert")
        {
            SqlConnection con = new SqlConnection("Data source=hobvision07; initial catalog=master; user id=sa; password=hobvision");

            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = "INSERT INTO quest_categories(cat_name,location,date) VALUES(@cat_name,@location,@date)"; cmd.Parameters.Add("@cat_name", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[0].Cells[3].Controls[0]).Text;
            cmd.Parameters.Add("@location", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[0].Cells[4].Controls[0]).Text;
            cmd.Parameters.Add("@date", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[0].Cells[5].Controls[0]).Text;
            cmd.Connection = con;

            con.Open();

            cmd.ExecuteNonQuery();

            con.Close();

        }

        else
        {
            SqlConnection con = new SqlConnection("Data source=hobvision07; initial catalog=master; user id=sa; password=hobvision");

            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = "UPDATE quest_categories SET cat_name=@cat_name,location=@location,date=@date WHERE cat_id=@cat_id";

            cmd.Parameters.Add("@cat_name", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[e.RowIndex].Cells[3].Controls[0]).Text;
            cmd.Parameters.Add("@location", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[e.RowIndex].Cells[4].Controls[0]).Text;
            cmd.Parameters.Add("@date", SqlDbType.VarChar).Value = ((TextBox)GridView1.Rows[e.RowIndex].Cells[5].Controls[0]).Text;
            cmd.Parameters.Add("@cat_id", SqlDbType.Int).Value = Convert.ToInt32(GridView1.Rows[e.RowIndex].Cells[2].Text);

            cmd.Connection = con;

            con.Open();

            cmd.ExecuteNonQuery();

            con.Close();



        }



        GridView1.EditIndex = -1;

        BindData();

    }
  

    protected void btnDelete_Click(object sender, EventArgs e)
    {
        ArrayList productsToDelete = new ArrayList();

        foreach (GridViewRow row in GridView1.Rows)
        {
            if (row.RowType == DataControlRowType.DataRow)
            {
                CheckBox chkDelete = (CheckBox)row.Cells[0].FindControl("chkDelete");

                if (chkDelete != null)
                {
                    if (chkDelete.Checked)
                    {
                        string productId = row.Cells[1].Text;
                        productsToDelete.Add(productId);
                    }
                }
            }
        }

        DeleteProducts(productsToDelete);
        BindData();
    }
    private void DeleteProducts(ArrayList productsToDelete)
    {

      
        foreach (GridViewRow row in GridView1.Rows)
        {
           
            string productId = row.Cells[2].Text;
            SqlConnection con = new SqlConnection("Data source=hobvision07; initial catalog=master; user id=sa; password=hobvision");
            SqlDataAdapter cmd = new SqlDataAdapter("delete from quest_categories where cat_id='" + productId + "'", con);
            DataTable dt = new DataTable();
            cmd.Fill(dt);
            GridView1.DataSource = dt;
            GridView1.DataBind();
           
            //BindData();
        }

      }
   }



Please help me regarding this.