public static function addChild(&$target, $primary_key, $level, $max_depth, &$children = array())
    {
        if (isset($children[$target[$primary_key]])) {
            $target['children'] = $children[$target[$primary_key]];
            if ($level + 1 < $max_depth) {
                foreach ($target['children'] as &$child) {
                    SC_Utils_Ex::addChild($child, $primary_key, $level++, $max_depth, $children);
                }
            }
        }
    }

<!--{* カテゴリ名表示 *}-->
<!--{assign var=disp_name value="`$child.category_id`.`$child.category_name`"}-->
<!--{if $child.level != $smarty.const.LEVEL_MAX}-->
    <a href="?" onclick="eccube.setModeAndSubmit('tree', 'parent_category_id', <!--{$child.category_id}-->); return false;">
    <!--{if $arrForm.parent_category_id == $child.category_id}-->
        <img src="<!--{$TPL_URLPATH}-->img/contents/folder_open.gif" alt="フォルダ" />
    <!--{else}-->
        <img src="<!--{$TPL_URLPATH}-->img/contents/folder_close.gif" alt="フォルダ" />
    <!--{/if}-->
    <!--{$disp_name|sfCutString:10:false|h}--></a>
<!--{else}-->
    <img src="<!--{$TPL_URLPATH}-->img/contents/folder_close.gif" alt="フォルダ" />
    <!--{$disp_name|sfCutString:10:false|h}-->
<!--{/if}-->