questo è il codice:
<?php
class database{
private $server = "localhost";
private $database = "ioPcms";
private $username = "";
private $password = "";
public $db=null;
function database() {
$this->db = new mysqli($this->server, $this->username, $this->password, $this->database);
}
function execquery ($query){
$result = $this->db->query($query);
if ($result->num_rows>0) {
while ($rs = $result->fetch_assoc()){
$temp[]=($rs);}}
return $temp;}}

?>

quando richiamo lo script mi da questa risposta:

Fatal error: Class 'mysqli' not found in /usr/local/apache2/htdocs/includes/database.php on line 9


cosa sbaglio?