TABLE
id    city_name
1     Union
2     Marthasville

$data = array('city_name', 'Marthasville');

//update record 2 from Marthasville to the same thing, Marthasville.
$this->db->where('id', 2);
$this->db->update('table', $data);

if($this->db->affected_rows() > 0)
{
    //I need it to return TRUE when the MySQL was successful even if nothing was actually updated.
    return TRUE;
}else{
    return FALSE;
}

if($this->db->affected_rows() >= 0){ }

$result = $this->db->update('table', $data);

if($result)
{
     //without error even no row updated
} else {

}