MySQL Multiplied query result (LEFT JOIN, SUM, COUNT, GROUP BY) - php

Question

Trying to get a simple SUM and COUNT from a table that takes a couple of joins and some math. I can't get it right.
I have 4 tables:
USERS
user_id, name
1, user1
2, user2
3, user3
4, user4
RESULTS
user_id, plus, minus
1, 1, 0
1, 1, 0
1, 1, 0
3, 0, 1
3, 1, 0
3, 1, 0
3, 1, 0
NOTES
user_id, note
1, lorem ipsum
3, abc
1, qwerty
3, qwerty
MESSAGES
user_id, message
1, lorem ipsum
3, abc
1, qwerty
3, qwerty
3, qwerty
3, qwerty
3, qwerty
I would like to sum all the result of subtracting plus from the minus, amount of notes and amount of messages of users.
My query:
SELECT u.`user_id`, SUM(w.`plus`-w.`minus`), COUNT(g.`user_id`), COUNT(m.`user_id`)
FROM `users` u
LEFT JOIN `results` w ON u.`user_id` = w.`user_id`
LEFT JOIN `notes` g ON u.`user_id` = g.`user_id`
LEFT JOIN `messages` m ON u.`user_id` = m.`user_id`
GROUP BY 1
Expected result should looks like:
user_id: sum(plus-minus) amount of notes, amount of messages
1: 3, 2, 2
3: 2, 2, 5
unfortunatelly query returns:
user_id: sum(plus-minus) amount of notes, amount of messages
1: 12, 12, 12
3: 20, 40, 40
Any help is greatly appreciated.

Answer 1

You should manually count the records in a subquery for every user_id so you will get correct value.
SELECT u.user_ID, u.Name,
COALESCE(r.totalResult, 0) totalResult,
COALESCE(n.totalNotes, 0) totalNotes,
COALESCE(m.totalMessages, 0) totalMessages
FROM users u
LEFT JOIN
(
SELECT user_ID, SUM(plus - minus) totalResult
FROM Results
GROUP BY user_ID
) r ON u.user_ID = r.user_ID
LEFT JOIN
(
SELECT user_ID, COUNT(*) totalNotes
FROM Notes
GROUP BY user_ID
) n ON u.user_ID = n.user_ID
LEFT JOIN
(
SELECT user_ID, COUNT(*) totalMessages
FROM Messages
GROUP BY user_ID
) m ON u.user_ID = m.user_ID
But if you have set an auto_incremented column in every table, the subquery isn't needed since you can distinctly count from it.