function action(){
        parent::action();
        $this->arrSubCatList = $this->lfGetCatTree($this->arrSearchData['category_id']);
    }
    function lfGetCatTree($parent_category_id, $count_check = false) {
        $objQuery =& SC_Query_Ex::getSingletonInstance();
        $objDb = new SC_Helper_DB_Ex();
        $col = '*';
        $from = 'dtb_category left join dtb_category_total_count ON dtb_category.category_id = dtb_category_total_count.category_id';
        // 登録商品数のチェック
        if ($count_check) {
            $where = 'del_flg = 0 AND product_count > 0 AND parent_category_id = ?';
        } else {
            $where = 'del_flg = 0 AND parent_category_id = ?';
        }
        $arrval = array($parent_category_id);
        $objQuery->setOption('ORDER BY rank DESC');
        return $objQuery->select($col, $from, $where, $arrval);
    }

    <!--▲ページナビ(本文)-->
<!--{* 下位カテゴリ *}-->
<!--{if $arrSubCatList|@count > 0}-->
    下位カテゴリ：
    <!--{foreach from=$arrSubCatList item=category}-->
        <a href="<!--{$smarty.const.ROOT_URLPATH}-->products/list.php?category_id=<!--{$category.category_id|h}-->"><!--{$category.category_name|h}--></a>&nbsp;
    <!--{/foreach}-->
<!--{/if}-->

SELECT
	*
FROM
	dtb_category left join 
	dtb_category_total_count ON dtb_category.category_id = dtb_category_total_count.category_id
WHERE
	del_flg = 0 AND parent_category_id = ?
ORDER BY rank DESC