Question

I have two tables

post Table
 post_id
 post_name
 post_summary
 date

post_reply Table
 parent_id
 post_id

So what I am doing is I inset a new post detail in post table and if there is any reply for that post then I put all the detail in post table itself and also stores the main post id as parent_id and replyed post id as post_id in post_reply.

Now I want to fetch all the posts and their reply under the main post if there is any and want to display the same on my jsp page.

I can’t write a single query to fetch these details. I can do it by first fetching all the post whose ids are not in post_reply and then loop on all post and then fetch the main post and replied post one by one.

I just want to fetch all these in one query. Is this possible? I am using mysql as database and using spring mvc with mybatis. So I am fecthing the whole list and putting it in my model attribute and display it on jsp page.

If someone can suggested me a better way of achieving this like changing my database structure or any other solution then that would be great.

Answer 1

table post

+---------+-------+---------+
| post_id | post  | comment |
+---------+-------+---------+
|       1 | kjasd | ajsdh   |
|       2 | abc   | dfgdfg  |
|       3 | ashdf | NULL    |
+---------+-------+---------+

table post_reply

+-----------+---------+
| parent_id | post_id |
+-----------+---------+
|         1 |       2 |
+-----------+---------+

Use this query it is working:

select *from post where post_id=1 or post_id in (select post_id from post_reply where parent_id=1);

It will return the reply with parent post and parent post only if there is no reply..