Feed select options from DB depending on another select options

Question

I have a form that has two select fields, one representing the region and one the name of the city/village/etc. I have a database with all these entries in the following for

Answer 1

Just use ajax for this, when one select change fetch data from the server to feed other select.

and you script.php should return JSON from db:

if (isset($_GET['region'])) {
    $sql = new mysqli('localhost','username','password','database');
    $region = mysqli_real_escape_string($sql,$_GET['region']);
    $query = "SELECT * FROM cities WHERE region = $region";
    $ret = $sql->query($query);
    $result = array();
    while ($row = $ret->fetch_assoc()) {
         $result[] = array(
             'value' => $row['id'],
             'name' => $row['city']
         );
    }
    echo json_encode($result);
}