PHP

<?php
 /**
  * why this variable $result?
  */
$result = array();

$rs = mysql_query("select * from dados where id=1");

while($row = mysql_fetch_array($rs))
{
    $node = array();
    $node['id'] = $row['id'];
    $node['text'] = $row['nome_cliente'];
    $node['state'] = 'closed';

    $node['children'] = has_child(3);
    /**
     * why this variable $result?
     */
    array_push($result,$node);
}

echo json_encode($result);

function has_child($id2){
 /**
  * why this variable $result?
  */
    $result2 = array();
    $rs = mysql_query("select id from dados where id = $id2");
    $row = mysql_fetch_array($rs);
    if($row === FALSE)
    {
        die('invalid id argument to has_child');
    }
    return $row[0];
}

output: [{"id":"1","text":"ds","state":"closed","children":"2"}]