Sort my post by meta value

Hi, I wanna sort my articles by meta value. I have following code

<?php
 $querystr = "
    SELECT wposts.*
    FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
    WHERE wposts.ID = wpostmeta.post_id
    AND wpostmeta.meta_key = 'review_score'
    AND wpostmeta.meta_value = 'review_score_value'
    AND wposts.post_status = 'publish'
    AND wposts.post_type = 'post'
    ORDER BY wposts.post_date DESC
 ";

 $pageposts = $wpdb->get_results($querystr, OBJECT);
$order = "&orderby=cost&order=DESC";
  $s2 = ' selected="selected"';
  if ($_POST['select'] == 'title') { $order = "&orderby=title&order=ASC"; $s1 = ' selected="selected"'; $s2 = ''; }
  if ($_POST['select'] == 'newest') { $order = "&orderby=cost&order=DESC"; $s2 = ' selected="selected"'; }
  if ($_POST['select'] == 'oldest') { $order = "&orderby=cost&order=ASC"; $s3 = ' selected="selected"'; $s2 = ''; }
  if ($_POST['select'] == 'ocena') { $pageposts = $wpdb->get_results($querystr, OBJECT);$s4 = ' selected="selected"'; $s2 = ''; }
?>
<form method="post" id="order">
  Sortuj:
  <select name="select" onchange='this.form.submit()'>
    <option value="title"<?=$s1?>> A-Z</option>
    <option value="newest"<?=$s2?>>newest</option>
    <option value="oldest"<?=$s3?>>oldest</option>
<option value="ocena"<?=$s4?>>score</option>
  </select>
</form>

By title ,newest, oldest work but score not really.
This code is ok?

AND wpostmeta.meta_key = 'review_score'
    AND wpostmeta.meta_value = 'review_score_value'