create table `comments`(
 `id` bigint unsigned not null AUTO_INCREMENT,
 `arc_id` bigint unsigned not null COMMENT '文章id',
 `user_id` bigint unsigned not null COMMENT '用户id',
 `comment_id` bigint unsigned not null DEFAULT '0' COMMENT '回复某个评论的id',
 `content` varchar(255) not null DEFAULT '' COMMENT '评论或回复的内容',
 `add_time` timestamp not null DEFAULT CURRENT_TIMESTAMP COMMENT '添加时间',
 PRIMARY KEY (`id`),
 KEY `arc_id` (`arc_id`)
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT '文章评论表';

/**
 * @param $arc_id  文章id
 * @param int $comm_id  评论id
 * @param array $result
 * @return array
 */
function getCommlist($arc_id, $comm_id = 0, &$result = array()){  //获取评论列表
 if(empty($arc_id)){
 return array();
 }
 $_where = "arc_id = {$arc_id} AND comment_id = {$comm_id}";
 $res = M('comments')->where($_where)->order('add_time DESC')->select();
 if(empty($res)){
 return array();
 }
 foreach ($res as $cm) {
 $thisArr = &$result[];
 $cm["_child"] = getCommlist($arc_id,$cm['id'],$thisArr);
 $thisArr = $cm;
 }
 
 return $result;
}

/**
 * @param $arc_id 文章id
 * @return array
 */
public function getCommlist($arc_id){
 if(empty($arc_id)){
 return array();
 }
 $res = M('comments')->where(array('arc_id'=>$arc_id))->order('add_time ASC')->select();
 $dataList = $stack = array();
 if($res){
 foreach($res AS $k=>$v){  //先将评论的数据进行入库（即comment_id=0）
  if($v['comment_id'] == 0){
  $v['_level'] = 0;  //设置层级数
  $v['_root'] = $v['id'];  //标识评论id
  array_push($stack,$v);  //入栈
  unset($res[$k]);
  }
 }
 
 while(!empty($stack)){
  $node = array_pop($stack);  //出栈
  $dataList[] = $node;
  foreach($res as $_k=>$_v){
  if($_v['comment_id'] == $node['id']){
   $_v['_level'] = $node['_level']+1;  //设置层级数
   $_v['_root'] = $node['_root'];  //标识评论id
   array_push($stack,$_v);  //入栈
   unset($res[$_k]);
  }
  }
 }
 }
 
 return $dataList;
}