asp.net gridview edit button doesn't update

When I enter new data and press update button it saves the old data (data that I want it to update).

public void fill()
{
    SqlCommand cmd = new SqlCommand("select * from school ",con );
    con.Open();
    SqlDataReader rd = cmd.ExecuteReader();

    GridView1.DataSource = rd;
    GridView1.DataBind();
    con.Close();
}

protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
    fill();
}

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{

    int id = int.Parse(((TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text);
    string  stu =((TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text;
    int age = int.Parse(((TextBox)GridView1.Rows[e.RowIndex].Cells[3].Controls[0]).Text);

    SqlCommand cmd = new SqlCommand("UPDATE school SET  stu_name=@stu_name,age=@age where id=@id ", con);
    cmd.Parameters.Add(new SqlParameter("@id", id));
    cmd.Parameters.Add(new SqlParameter("@stu_name", stu));
    cmd.Parameters.Add(new SqlParameter ("@age",age));

    con.Open();
    cmd.ExecuteNonQuery();
    con.Close();

    GridView1.EditIndex = -1;
    fill();
}

he problem that the values that assigned to name,age are the existing values in the database not the new values which I entered in the runtime any one can help me?? thanks in advance

Tags: C#, ASP.NET, Gridview