How to select an id bigger then

Question

I'm working on a news system for a website. I used the news system from this tutorial: http://pixelcode.co.uk/tutorials/php/mysql-news-system/

So to display the news I use this line of code:

if(!$_GET['id'])
        {   
            $query = mysql_query("SELECT * FROM news ORDER BY id DESC");
            while($output = mysql_fetch_assoc($query))
            {
                    echo '<div id="nieuws">';
                    echo '<a href="?id='.$output['id'].'" id="link">';                      
                    echo '<h1>'.$output['title'].'</h1>';
                    echo '<span id="date">'.date('d-m-y', $output['date']).'</span><br / >';
                    echo $output['shortnews'].'<br / >';
                    echo '</a>';
                    echo '</div>';      
            }

        }
        else
        {
            $id = $_GET['id']; 
            $query = mysql_query("SELECT * FROM news WHERE id='$id'");
            $output = mysql_fetch_assoc($query);                
    ?>      
            <form method="post" action="?id=<? echo $output['id']; ?>"> 

            <h1><? echo $output['title']; ?></h1>
            <? echo '<span id="date">'.date('d-m-y', $output['date']).'</span><br / >' ?>
            <? echo $output['news']; ?>
            </form>
    <?php } ?>

I can do: if(!$_GET['id'] = 6) but I can't do this: if(!$_GET['id'] > 6). What's the problem? Or is there another code for bigger then an id?

Thanks for replying, MARCH

Answer 1

Operator precedence: ! binds tighter than ==, so you're effectively doing

(not($_GET) == 6)

That's why there's != for inequality tests.

If you'd used proper bracketing, e.g

(!($_GET['id'] == 6)) 

then you'd be doing

not(id == 6) 

and get your expected results, because that's logically/functionally equivalent to id != 6

And note that you're vulnerable to sql injection attacks and are using an obsolete/deprecated DB interface.