而循环过滤器类别

I have a very basic setup: A table called "elements" and which has columns "positive","negative","type" and I need to select all the elements and loop only through the ones that have a type of "video". Here's what I have now:

require_once 'dbcon.php';

    $stmt = $db->prepare("select positive, negative,type from elements");
    $stmt->bind_result($pos,$neg$type);
    $stmt->execute();

    while($stmt->fetch()){
        echo $type
    }

I've tried with a if($type=='video') and while(($stmt->fetch()) && ( $type=='video )) , but I don't get any results back.

So you need to apply WHERE in query itself:

SELECT `positive`, `negative`, `type` FROM `elements` WHERE `type`='video'