GridView OnRow Updating

if(!IsPostBack)
{
    //Bind your gridview here.
}

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
            GridViewRow row = GridView1.Rows[e.RowIndex];
            string constr = ConfigurationManager.ConnectionStrings["connstr"].ToString();
            SqlConnection con = new SqlConnection(constr);

            string id = (((Label)row.FindControl("lblid")).Text).ToString();

            string comments = (((TextBox)row.FindControl("txtcomments")).Text).ToString();
           // string grant = (((CheckBox)row.FindControl("CheckBox1")).Checked).ToString();

            if (((CheckBox)row.FindControl("CheckBox1")).Checked == true)
                {
                    con.Open();
                    SqlCommand CmdSql = new SqlCommand("Update leave set admin_comments='" + comments + "', granted='" + true + "' where id=" + id + " ", con);
                    CmdSql.ExecuteNonQuery();
                    GridView1.EditIndex = -1;
                    con.Close();
                    gridpop();
                }

                else
                {
                    con.Open();
                    SqlCommand CmdSql = new SqlCommand("Update leave set admin_comments='" + comments + "', granted='" + false + "' where id=" + id + " ", con);
                    CmdSql.ExecuteNonQuery();
                    GridView1.EditIndex = -1;
                    con.Close();
                    gridpop();

                }
    }