function display_ul($i,$var='0'){

    global $dsql;

    $row = $dsql->GetOne("SELECT COUNT(id) as num FROM 58pic_arctype  WHERE reid = $i)");

    if($row['num']>0 ){

        if($var=='0'){

           return "<ul>"; 

        }else{

           return "</ul>";  

        }

    }

}

{dede:channelartlist row=7 typeid=top currentstyle=current}

<li>

    <a href="{dede:field.typeurl/}">{dede:field.typename/}</a>

    {dede:field.id function='display_ul(@me)'/}

        <!-- 二级栏目 -->

        {dede:channel type=son noself=yes}

        <li>

            <a href="[field:typelink/]">[field:typename/]</a>

        </li>

        {/dede:channel}

    {dede:field.id function='display_ul(@me,1)'/}

</li>

{/dede:channelartlist}