How to design the mysql table structure for nested display of article comments (in the form of NetEase news comments)

Now there is a post table (the structure cannot be changed)
tid topic pid
pid reply id

Now a new comment nesting display function is added, that is, tid=1
a commented a comment with a pid of 1
b replied to a's comment with a pid of 2
c replied to b's comment with a pid of 3
d replied to a with a pid of 3 4

Displayed as
1st floor pid1
2nd floor pid1,pid2
3rd floor pid1,pid2,pid3
4th floor pid1,pid4
That is, every reply to others needs to quote all previous replies.
(The format is the same as the comments on NetEase News)
I currently think of a structure that is post_conversation pid, to_pid
In this way, the 2nd floor reply will insert 2,1

<code> 3楼回复就插入两条     3,1
                     3,2
 4楼回复就插入         4,1          </code>

If there is a conversation on the 99th floor, 98 pieces of data must be inserted

<code>这样有个好处就是可以很方便取出任意一个pid的评论情况
select topid from post_conversation  where pid = 'xxx' order by pid ;
但是会造成多的重复数据  一个99楼对话得插入1+2+3+。。。+99条
</code>

If post_conversation is designed like this
pid, parent_pid (the pid being replied to)
The amount of data is small (only one message is inserted for each reply);
But querying all conversations for each pid is very troublesome (I am thinking of recursive query database);

<code>select parent_pid from post_conversation  where pid = 'xxx'
    select parent_pid from post_conversation  where pid = 'parent_pid '
        ...
        一直到parent_pid 为0为止，查询出所有的对话pid
</code>

Do you have any good suggestions?

tid topic pid
pid reply id

a commented a comment with a pid of 1
b replied to a's comment with a pid of 2
c replied to b's comment with a pid of 3
d replied to a with a pid of 3 4

1st floor pid1
2nd floor pid1,pid2
3rd floor pid1,pid2,pid3
4th floor pid1,pid4
That is, every reply to others needs to quote all previous replies.
(The format is the same as the comments on NetEase News)
I currently think of a structure that is post_conversation pid, to_pid
In this way, the 2nd floor reply will insert 2,1

<code> 3楼回复就插入两条     3,1
                     3,2
 4楼回复就插入         4,1          </code>

<code>这样有个好处就是可以很方便取出任意一个pid的评论情况
select topid from post_conversation  where pid = 'xxx' order by pid ;
但是会造成多的重复数据  一个99楼对话得插入1+2+3+。。。+99条
</code>

pid, parent_pid (the pid being replied to)
The amount of data is small (only one message is inserted for each reply);
But querying all conversations for each pid is very troublesome (I am thinking of recursive query database);

<code>select parent_pid from post_conversation  where pid = 'xxx'
    select parent_pid from post_conversation  where pid = 'parent_pid '
        ...
        一直到parent_pid 为0为止，查询出所有的对话pid
</code>

I used to use the most primitive recursive query method to achieve infinite nesting (menus, comments). Later, I saw an article posted by the administrator in the Laravel-China community, the article address is https://laravel-china.org/topics/2124, using the

pre-sorted traversal tree algorithm (Nested set model)
to achieve infinite tree levels Model (tag system, menu system, comment system, etc.). The subject can refer to the following.

One article corresponds to multiple comments, and one comment corresponds to multiple replies.

Q&A communities segmentfault.com and Tencent News They all use "reply to comments".
Take segmentfault as an example:
The questioner (poster) posted a question, and this question has multiple answers (layer owners), which is a one-to-many relationship in the database.
Each An answer can have multiple replies, which is also a one-to-many relationship.

<code>question(id,            user_id,content)
answer  (id,question_id,user_id,content)
reply   (id,answer_id,  user_id,content)</code>