Hi everybody,
I have a problem with slecting with 2 table here is the definition:

Table1: forum_topics (id_topic,subject ,topic_date)
Table2: forum_posts (id_post,id_topic,id_user,post,post_date)

as you can guess table 1 keeps the topics and table 2 contains the posts for topics.

Now I want to display last 10 topics on homepage with following data:
- name of topic,
- the id_user who posted last to the topic
and want to order them in a way that the topic which has the last post will be displayed at top.

is it posibble to make all with one query. Or is it a better way to handle it with php? Which one is faster? which one is reliable?

If it is posible to make it with one query how can I do this. I tried some querries but cant order it by last post

Thanks for your help.

this is faster and way more reliable:

Thank you sooo much r937,
query works fine but I need to group by id_topic because I want to display each topic once.
When I try grouping it, result don't come up with id_user who posted last to the topic

I know it is possible to get last poster with a new query in php while statement but this means making the same thing with 11 queries instead of one. I think this is not the best way.

Another way I can think is to push redundant data to forum_topics. (a new field like last_poster_id and updating it for each post). But I know this also is not a good approach.

Any ideas??

what does "i need to group by id_topic" mean?

the query i gave you will return exactly one row per topic

Practically yes it is , but when I try not!

Because I noticed that I have posts that has exactly the same timestamp on my table which I use to test.

Now i changed and it works.

I thank you r937.