模板中不需要SQL查询。

function wpse_72594_get_attachments( $id, $mime = \'\' )
{
    $args = array(
        \'post_type\' => \'attachment\',
        \'post_mime_type\' => $mime,
        \'post_parent\' => $id
    ); 
    $attachments = get_posts($args);
    if ($attachments) 
        return $attachments;

    return false;
}

• wpse_72594_get_attachments(300), 抓取所有附件wpse_72594_get_attachments(300, \'image\' ), 仅图像wpse_72594_get_attachments(300, \'application/pdf\' ), 仅pdf文件