Question

I have 3 tables in MySQL

USERS
uid
email
password
created

This is the table that have all records of all users

PHOTOS
iid
uid
file
thumb
uploaded

This is the table where all photos posted by each user are kept on

COMMENTS
cid
iid
uid
message
created

This is the table where all the comments on each photo by every user are kept on

What i want is a query that retrives me the amount (COUNT) of comments on every photo for every unique (DISTINCT) user.
For example (the resulting output must be) :

comment_amount  by_user on_picture
3               1       1
2               2       1
2               1       2
5               2       2
6               2       3

so the output could tell us if it is formated something like (example)

3 comments posted by USER1 on PICTURE1
2 comments posted by USER2 on PICTURE1

2 comments posted by USER1 on PICTURE2
5 comments posted by USER2 on PICTURE2

6 comments posted by USER2 on PICTURE3

What i have so far is

SELECT 
users.uid
FROM users
INNER
    JOIN photos
    ON photos.uid = users.uid
INNER
    JOIN comments
    ON comments.iid = photos.iid
    

and here is the sandbox testing

http://sqlfiddle.com/#!2/955d5/1
    

But I don’t know what to do next. Also any language besides MySQL should work as well!

Answer 1

SELECT count(*) AS comment_amount, users.uid AS by_user, photos.iid AS on_picture
FROM users
INNER
    JOIN photos
    ON photos.uid = users.uid
INNER
    JOIN comments
    ON comments.iid = photos.iid
group by users.uid, photos.iid

or just

SELECT count(*) AS comment_amount, uid AS by_user, iid AS on_picture
FROM comments

if you just need the data in the comments table