Populate custom meta box from database

I want to populate a series of checkboxes from a database table that I have filled with values myself, i.e. it’s not a wordpress table, but in the same database.

This is what I have done in the none wordpress parts of my site, that works perfectly

$query = "SELECT genre_id, genre_name FROM genres ORDER BY genre_name ASC";
	$result = mysqli_query ($dbc, $query) or trigger_error ("query: $query\n<br />MySQL Error: " . mysqli_error($dbc));

	while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
		echo '<div class="genre_checkbox"><input type="checkbox" name="genre[]" value="' . $row['genre_name'] . '">' . $row['genre_name'] . '</div>';
	}

However, this doesn’t work in wordpress of course.

This is what I have so far:

add_action("admin_init", "genre_fields");

function genre_fields(){
	add_meta_box('event_genres', 'Genres', "event_genre_options", "event", "normal");
}

function event_genre_options(){

	global $post;
	global $wpdb;

	include(EVENT_CALENDAR_DIR . "event_class.php");

	$event = new Manage_events;

	$data = $event->get_event($post->ID);

	$rows = $wpdb->get_results( "SELECT genre_id, genre_name FROM genres ORDER BY genre_name ASC", ARRAY_A);

	while ($rows = mysql_fetch_array($result, MYSQLI_ASSOC)) {
		echo '<div class="genre_checkbox"><input type="checkbox" name="genre[]" value="' . $row['genre_name'] . '">' . $row['genre_name'] . '</div>';
	}
}

As you can see I’m much more familiar with standard PHP and mySQL syntax and I can’t find what I need in the reference for WP.

Any help would be hugely appreciate.

Thankyou

And i’m getting:

mysql_fetch_array() expects parameter 1 to be resource, null given