In php manual <http://php.net/manual/en/mysqli-stmt.bind-param.php>

I see code like this:

```
$stmt->bind_param('sssd', $code, $language, $official, $percent);

$code = 'DEU';
$language = 'Bavarian';
$official = "F";
$percent = 11.2;

/* execute prepared statement */
$stmt->execute();

```