Problem with checkboxes. please help.

ID    Pages           Add     View    Edit    Delete
1     Checkin         N       NULL    NULL    NULL
2     Checkout        N       NULL    NULL    NULL
3     UserCreation    N       NULL    NULL    NULL
4     AssetType       N       NULL    NULL    NULL
5     VendorDetails   N       NULL    NULL    NULL
6     CustomerDetails N       NULL    NULL    NULL
7     ItemStatus      N       NULL    NULL    NULL
8     ComanyDetails   N       NULL    NULL    NULL
NULL  NULL            NULL    NULL    NULL    NULL

 protected void Button3_Click(object sender, EventArgs e)
    {

        //for (int i = 0; i < GridView1.Rows.Count; i++)
        //{
        //    CheckBox chk = (CheckBox)GridView1.Rows[i].Cells[2].FindControl("CheckBox1");
        //    if (chk != null)
        //    {
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            GridViewRow row = GridView1.Rows[i];
            bool isChecked = ((CheckBox)row.FindControl("CheckBox1")).Checked;

            if (isChecked)
            {

                // if (!Page.IsPostBack)

                string strID = GridView1.Rows[i].Cells[0].Text;
                string Pages = GridView1.Rows[i].Cells[1].Text;
                string status = "Y";

               
                con.Open();
                string query ="Update Role1  set [Add] ='" + status + "' where ID= '" + strID + "'  and Pages= '" + Pages + "'";
                SqlCommand cmd = new SqlCommand(query,con);
               cmd.ExecuteNonQuery();

                GridView1.DataBind();
                con.Close();
            }


            else
            {

                string strID = GridView1.Rows[i].Cells[0].Text;
                string Pages = GridView1.Rows[i].Cells[1].Text;
                string status = "N";


                
                //cmd = new SqlCommand("insert into Role1(Checkin_Add) values(" + status + " where ID= '" + strID + "' and Role_Name='" + strName + "')", con);
              string query = "Update Role1  set [Add] ='" + status + "' where ID= '" + strID + "'  and Pages= '" + Pages + "'";
                SqlCommand cmd = new SqlCommand(query, con);
                con.Open();
                cmd.ExecuteNonQuery();
                
                GridView1.DataBind();
              con.Close();
            }
        }   
    }     
}