public function update(Alert $alert){
$query = $this->_db->prepare(' UPDATE t_alert SET
alert=:alert, status=:status, updated=:updated, updatedBy=:updatedBy
WHERE id=:id')
or die (print_r($this->_db->errorInfo()));
$query->bindValue(':id', $alert->id());
$query->bindValue(':alert', $alert->alert());
$query->bindValue(':status', $alert->status());
$query->bindValue(':updated', $alert->updated());
$query->bindValue(':updatedBy', $alert->updatedBy());
$query->execute();
$query->closeCursor();
}