Hi Mindstickians!

I have a code like this:

$genre = 'jazz';

$what_genre = mysql_real_escape_string($genre);

$query = mysql_query("SELECT song.id, song.title, genre.genre FROM song INNER JOIN genre ON song.id_genre=genre.id_genre WHERE genre.genre = '" .$what_genre. "' ORDER BY id");

if(mysql_num_rows($query) > 0)

{

    while($result = mysql_fetch_array($query))

    {

        echo $result['id'];

        echo $result['title'];

        echo $result['genre'];

    }

}

I want to show the result, but it failed. The system give me an error report:

A PHP Error was encountered

Severity: Warning

Message: mysql_num_rows() expects parameter 1 to be resource, boolean given

What should I do?

Thanks in advance!