Displaying custom taxonomy in the admin list of a custom post type

Always check the codexget_terms( $taxonomies, $args ) – your code should read:

$genre = get_terms( 'genre', array(
    'include' => get_post_meta( $post->ID, 'maingenre', true ),
));

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)