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function showCats($dataId) {
    $return = '';
    $dataId = (int) $dataId;
    $subCatsArray = array();
    $catsIds = mysql_query("SELECT DISTINCT(c.name) as cat_name, c.id as cat_id, d.id AS data_id  FROM
        categories c,
        data_category dc,
        data d
        WHERE
        c.id=dc.maincat_id AND d.id=dc.data_id AND d.id='$dataId'");
    if (mysql_num_rows($catsIds) != 0) {
        $return.='<b>Категории:</b>';
        while ($cat = mysql_fetch_object($catsIds)) {
            $return.='<a href="?cat='.$cat->cat_id.'">'.$cat->cat_name.'</a>';
            $subCats = mysql_query("SELECT dc.name AS name, dc.id AS subcat_id FROM data_categories dc
                WHERE dc.id IN(SELECT id FROM data_category WHERE data_id='".$dataId."')");
            while ($subcat = mysql_fetch_object($subCats)) {
                $subCatsArray[] = '<a href="?cat='.$cat->cat_id.'&subcat='.$subcat->subcat_id.'">'.$subcat->name.'</a>';
            }
            $return.='<br>('.implode(',', $subCatsArray).')';
        }
        return $return;
    }
}