PHP serve json

<?php
//Send proper content-type
header('Content-Type: application/json');
if(isset($_POST['id'])) {
    //Get data from database here
    //and serve it with
    //json_encode()
    echo json_encode(
        array(
            array('id' => 1, 'name' => 'Human'),
            array('id' => 2, 'name' => 'Orc'),
            array('id' => 3, 'name' => 'Dwarf'),
        )
    );
}
?>