Join query returning empty as well - mysql

Question

I have three tables (many more cols but listed important ones):
users
user_id - name
1 DAN
2 TED
3 SAM
list_shares
list_shares_id - user_id - list_id
1 1 123
2 3 123
3 2 456
list_contribute
list_contr_id - list_id - can_contribute
1 123 3
I want to show all users who are in table list_shares under a list_id, join that with users table to get user info, and also count how many of them are also in the contribute table
Basically - a user can share a list with users and also invite some of the users to contribute, but not all those sharing are allowed to contribute, hence the separate list_contribute table.
here's what I'm using firstly which just shows all users with a certain ID:
select u.name, u.live_prof_pic, u.url, u.user_id from list_shares ls
join users u on ls.user_id = u.user_id
where ls.list_id = '123'
This brings up two results, which is correct - the next query is trying to find which of these two are in the list_contribute table also - but, it reduces the result to one whereas i want it to return both and show 0 for how_many if not in list_contribute
select u.name, u.live_prof_pic, u.url, count(ls.list_shares_id) as how_many, u.user_id from list_shares ls
join users u on ls.user_id = u.user_id
left join list_contribute lc on ls.list_id = lc.list_id
where ls.list_id = '123'
In the above data i want to return
user_id name how_many
3 SAM 1
1 DAN 0

Answer 1

Add a GROUP BY to make it a standard SQL aggregate
select u.name, u.live_prof_pic, u.url, count(ls.list_shares_id) as how_many, u.user_id
from
list_shares ls
join users u on ls.user_id = u.user_id
left join list_contribute lc on ls.event_id = lc.event_id
where ls.list_id = '123'
group by u.name, u.live_prof_pic, u.url, u.user_id
MySQL has a rubbish extension that tries to remove the requirement but gives incorrect data often
Edit, after comment.
You should still use correct GROUP BY syntax
However, your COUNT should be COUNT(lc.event_id) to count child rows.

Answer 2

Use query below if it does not return desired result set, it means you have orphaned record sets in list_shares which does not have corresponding users.
select
u.name
, u.user_id
, count(lc.list_id) as how_many
from
list_shares ls
INNER JOIN
users u
on
ls.user_id = u.user_id
left join
list_contribute lc
on
ls.list_id = lc.list_id
where
ls.list_id = '123'
GROUP BY
u.name
, u.user_id
Not sure how mysql count works so to be 100% sure:
select
u.name
, u.user_id
, SUM(CASE WHEN lc.list_id IS NOT NULL THEN 1 ELSE 0 END CASE) as how_many
from
list_shares ls
INNER JOIN
users u
on
ls.user_id = u.user_id
left join
list_contribute lc
on
ls.list_id = lc.list_id
where
ls.list_id = '123'
GROUP BY
u.name
, u.user_id

Answer 3

If I got you right - here's what you need
SQL Fiddle Example
select
u.user_id, u.name,
count(case when lc.can_contribute = u.user_id then 1 else null end) as HowMany
from users as u
inner join list_shares as ls on ls.user_id = u.user_id
inner join list_contribute as lc on lc.list_id = ls.list_id
group by
u.user_id, u.name