树节点MySQL到PDO语句

Question

I need help. I have a tree code in mysqli and I'm trying to translate it into PDO statement. Any advice? Thanks before

PHP:

while($row = mysql_fetch_array($rs)){
            $node = array();
            $node['id'] = $row['id'];
            $node['text'] = $row['name'];
            $node['state'] = has_child($row['id']) ? 'closed' : 'open';
            array_push($result,$node);
        }

   function has_child($id)
   {
     $rs = mysql_query("select count(*) from
     nodes where parentId=$id");
     $row = mysql_fetch_array($rs);
     return $row[0] > 0 ? true : false;
   }

Create Table SQL:

    CREATE TABLE `nodes` (
          `id` int(11) NOT NULL AUTO_INCREMENT,
          `parentId` int(11) DEFAULT NULL,
          `name` varchar(50) DEFAULT NULL,
          PRIMARY KEY (`id`)
        ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

Insert SQL:

INSERT INTO `nodes` VALUES 
    ('1', '0', 'Node 1'), 
    ('2', '0', 'Node 2'), 
    ('3', '0', 'Node 3'), 
    ('4', '0', 'Node 4'), 
    ('5', '1', 'Node 1.1'), 
    ('6', '1', 'Node 1.2'),
    ('7', '5', 'Node 1.1.1'), 
    ('8', '5', 'Node 1.1.2'), 
    ('9', '5', 'Node 1.1.3');

Answer 1

$result=array();
try{
$query->execute();  
while($row =$query->fetch(PDO::FETCH_ASSOC)){
$node = array();
$node['id'] = $row['id'];
$node['text'] = $row['name'];
$node['state'] = $this->has_child($row['id']) ? 'closed' : 'open';
array_push($result,$node);
}
}catch(PDOException $e){
    die($e->getMessage());}
    return json_encode($result);    
}

Thank you all....