SQL query to get 10 last topics with replies - sql

Question

I have a simple forum database and want to write SQL query to get
10 last topics (threads) with replies from 3 or more unique posters.
Result: Topic (thread) name | Last message text | User name | Date
UPDATED:
Here is what I tried:
SELECT thread.thread_id, thread.thread_name, message.thread_id,
COUNT(message.thread_id)
FROM thread, message
WHERE message.thread_id = thread.thread_id
GROUP BY message.thread_id
HAVING COUNT(message.thread_id) >= 3
LIMIT 10
But it returns 10 topics (threads) with 3 or more replies (but not 3 or more unique posters)
UPDATE 2:
SELECT message.thread_id AS ID, thread.thread_name AS topic
FROM message INNER JOIN thread
ON message.thread_id = thread.thread_id
GROUP BY message.thread_id
HAVING COUNT(*) >= 3
LIMIT 10
This also returns 10 topics with 3 or more replies
UPDATE 3, thanks #shawnt00
SELECT thread.thread_name AS 'Topic', message_text AS 'Message', person_nickname AS 'Nickname', message_date AS 'Date'
FROM thread,
(
SELECT thread.thread_id, MAX(message_date) AS last_date
FROM thread
INNER JOIN message ON message.thread_id = thread.thread_id
GROUP BY thread.thread_id
HAVING COUNT(DISTINCT message.person_id) >= 3
) AS temp
INNER JOIN message
ON message.thread_id = temp.thread_id AND message.message_date = temp.last_date
INNER JOIN person ON person.person_id = message.person_id
WHERE thread.thread_id = temp.thread_id
ORDER BY message.message_date DESC
LIMIT 10

Answer 1

with data as (
select p.thread_id, max(message_date) as last_date
from thread t inner join message m on m.thread_id = t.thread_id
group by p.thread_id
having count(distinct m.person_id) >= 3
)
select *
from data d
inner join message m
on m.thread_id = d.thread_id and m.message_date = m.last_date
inner join person p on p.person_id = m.person_id;
The only assumption is that there can't be ties on dates. If you have analytic functions available then there are other approaches using those. I'm sure you can figure out how to get top 10.

Answer 2

i think you need below query.
Assuming that you are using mysql so i used Limitfunction as you want last 3 unique row
select distinct th.thread_name as Topic_name, m.message_text, p.person_nickname as User_name, m.message_date as Date from message m
inner join thread th on m.thread_id=th.thread_id
inner join persion p on p.persion_id=m.persion_id
order by message_date desc
Limit 3
But if the db is SQLSERVER Then use below query
select distinct TOP(3) th.thread_name as Topic_name, m.message_text, p.person_nickname as User_name, m.message_date as Date from message m
inner join thread th on m.thread_id=th.thread_id
inner join persion p on p.persion_id=m.persion_id
order by message_date desc