Custom query and Custom Fileds

Hello. this custom query is showing all posts from all categories.
as i defiend a term_id( Cat ID) but it is still showing the all posts from all categories.
some1 can help me?

<?php $category= get_query_var(‘cat’) ?>

<?php

$querystr = “
SELECT *
FROM wp_posts AS wposts, wp_postmeta AS wpostmeta, wp_terms AS wterms
WHERE wposts.ID = wpostmeta.post_id
AND wpostmeta.meta_value = ‘$dd’
AND wterms.term_id = ‘$category’
ORDER BY wpostmeta.meta_value DESC
“;

$pageposts = $wpdb->get_results($querystr, OBJECT);
?>