Generating user post count and thread count from different tables - mysql

Question

So I don't know much about MySQL but I heard about views and I'm trying to wrath my head around it.
Basically what I want to do is
check the table forum_posts, count the number of posts made by each user
query forum_users for each user to get every column and add to the view
query forum_threads to get the number of threads made by that user.
I don't know if that order is correct performance-wise but the final view should in theory look like either
1.
UId (user id from forum_users)
UName (user name from forum_users)
UThreads (user thread count)
UPosts (user post count)
UFakePosts (named UPosts in forum_users, I'll rename that later to UFakePosts)
ULastPost (this one is not that important but I'm just throwing it here in case anyone knows how to do it, I imagine it would be possible by selecting the post with the biggest PDate column)
2.
All of forum_users but renaming the forum_users.UPosts and forum_users.UThreads to UFakePosts and UFakeThreads
ULastPost
UThreads (user thread count)
UPosts (user post count)
I managed to get the post count working by using the following code
SELECT
IFNULL(a.UId,-1) AS UId,
IFNULL(a.UName,'Unknown') AS UName,
postsquery.Posts AS UPosts,
IFNULL(a.UPosts,-1) AS UFakePosts
FROM
(
SELECT p.PId, p.PAuthorId, COUNT(p1.PAuthorId) as Posts
FROM forum_posts AS p
LEFT JOIN forum_posts AS p1 ON p1.PId = p.PId
GROUP BY p.PAuthorId
)
AS postsquery
LEFT JOIN forum_users AS a ON postsquery.PAuthorId = a.UId
ORDER BY postsquery.Posts DESC
which generates the following result
but no success with getting threads, I can get one of the other but not both at the same time.
I've also tried this
SELECT IFNULL(a.UId,-1) AS UId,
IFNULL(a.UName,'Unknown') AS UName,
postsquery.Posts AS UPosts,
threadsquery.Threads AS UThreads,
IFNULL(a.UPosts,-1) AS UFakePosts
FROM
(
SELECT p.PId, p.PAuthorId, COUNT(p.PAuthorId) as Posts
FROM forum_posts AS p
)
AS postsquery
LEFT JOIN forum_users AS a1 ON postsquery.PAuthorId = a1.UId,
(
SELECT t.TId, t.TAuthorId, COUNT(t.TAuthorId) as Threads
FROM forum_threads AS t
GROUP BY t.TAuthorId
)
AS threadsquery
LEFT JOIN forum_users AS a ON threadsquery.TAuthorId = a.UId
ORDER BY
postsquery.Posts DESC
.....but the results are wrong:
What's supposed to happen:
Unknown (user that I haven't scraped yet): 1 post / 0 threads
User1: 2 posts / 0 threads
User2: 1 post / 2 threads
User3: 0 posts / 0 threads
If I could do another view but for threads, getting number of unique posters and number of posts that would be cool as well but one thing at a time.
Fiddle with database structure
http://sqlfiddle.com/#!9/c93d9/1
Structure should be pretty easy to understand, U stands for user, T for thread, P for post, D for date and so on.

Answer 1

Create a subselect to get the thread count:
LEFT JOIN
(
SELECT
TAuthorId,
COUNT(1) as thread_count
FROM
forum_threads
GROUP BY
TAuthorId
) threads ON
threads.TAuthorId = postsquery.PAuthorId
And then select that column:
IFNULL(threads.thread_count, 0) as thread_count
Putting it all together:
SELECT IFNULL(a.UId,-1) AS UId, IFNULL(a.UName,'Unknown') AS UName, IFNULL(postsquery.Posts, 0) AS UPosts, IFNULL(threads.thread_count, 0) as thread_count, IFNULL(a.UPosts,-1) AS UFakePosts
FROM
(
SELECT p.PId, p.PAuthorId, COUNT(p1.PAuthorId) as Posts
FROM forum_posts AS p
LEFT JOIN forum_posts AS p1 ON p1.PId = p.PId
GROUP BY p.PAuthorId
)
AS postsquery
LEFT JOIN forum_users AS a ON postsquery.PAuthorId = a.UId
LEFT JOIN
(
SELECT
TAuthorId,
COUNT(1) as thread_count
FROM
forum_threads
GROUP BY
TAuthorId
) threads ON
threads.TAuthorId = postsquery.PAuthorId
ORDER BY
postsquery.Posts DESC