using result from xml parsing like as query of mysql

my code is like this..

$url = array("http://ift.tt/1CZFO4W"
                 " ............ "
                 " ............ " );

for($j=0;$j<count($url);++$j){

    $num = $j + 1;      
    echo "<h1>".$num."</h1><p class='url'>".$url[$j]."</p><br>";    

     $xmlDoc = new DOMDocument();
     $xmlDoc->load($url[$j]);        

     //get elements from "<channel>"
     $channel=$xmlDoc->getElementsByTagName('channel')->item(0);
     $channel_title = $channel->getElementsByTagName('title')->item(0)->childNodes->item(0)->nodeValue;
     $channel_link = $channel->getElementsByTagName('link')->item(0)->childNodes->item(0)->nodeValue;
     $channel_desc = $channel->getElementsByTagName('description')->item(0)->childNodes->item(0)->nodeValue;

     //output elements from "<channel>"     
     echo("<p><a href='" . $channel_link  . "'>" . $channel_title . "</a><br>" . $channel_desc . "</p>");

     $x=$xmlDoc->getElementsByTagName('item');

     for ( $i = 0 ; $i < $x->length ; ++$i ){ 

       $item_title=$x->item($i)->getElementsByTagName('title')->item(0)->childNodes->item(0)->nodeValue;
       $item_link=$x->item($i)->getElementsByTagName('link')->item(0)->childNodes->item(0)->nodeValue;
       $item_desc=$x->item($i)->getElementsByTagName('description')->item(0)->childNodes->item(0)->nodeValue;

        $query[$i]['title'] = $item_title;
        $query[$i]['field'] = "xml";
        $query[$i]['id'] = $item_link;
        $query[$i]['description'] = $item_desc;    
     }  

/*   echo "<pre>";
        print_r($channel);          
         echo "</pre>";
*/
}

And I want to use url array like a query of mysql and I coding like this.

$url = mysql_fetch_assoc($query);

And I got error message: Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, array given in .....

How can I solve this?