Check if records exists in join and assign and count it

Question

Im making an application where its possible to vote on pictures. Im doing some joins and would like to check each picture i get, if the user logged in has voted on it.

My votes table setup is like this:

+-------------------------+
| id | user_id | photo_id |
+-------------------------+
|  1 |    2    |     6    |
+-------------------------+
|  2 |    4    |     5    |
+-------------------------+
|  3 |    3    |     5    |
+-------------------------+
|  4 |    1    |     6    |
+-------------------------+

Im joining 3 tables:

users, photos and votes

SELECT 
    users.*, 
    photos.*, 
    users.id as user_userid, 
    photos.id as photo_photoid, 
    COUNT(votes.id) as totalvotes 
FROM
    photos 
LEFT JOIN 
    votes 
ON 
    votes.photo_id = photos.id 
LEFT JOIN
    users 
ON 
    users.id = photos.author_id 
GROUP BY
    photos.id 
ORDER BY
    totalvotes 
DESC

I would like to make a query inside this sql that does something like this:

+---------------------------------------------------------------------------------+
| photo_photoid | user_userid | totalVotes | currentUserHasVotetThisAmountOfTime  |
+---------------------------------------------------------------------------------+
|        6      |      1      |      2     |                 1                    |
+---------------------------------------------------------------------------------+
|        5      |      1      |      2     |                 0                    |
+---------------------------------------------------------------------------------+

So i guess im looking for a count of the records, where votes.user_id = $MyLoggedInUser AND votes.photo_id = photo.id

Any suggestions?

Answer 1

Here is your request :

SELECT
  v.photo_id,
  COUNT(v.id) AS total_votes,
  (SELECT COUNT(id) FROM vote WHERE photo_id = v.photo_id AND user_id = 1) AS currentUserHasVotetThisAmountOfTime  
FROM
  vote AS v
GROUP BY
  v.photo_id
ORDER BY
  total_votes
  DESC

Just replace user_id = 1 by your own ID (in the sub-request line 4).

I get ride of the user_id column, since this is your something you provide there is imo no point to return this in the query as well.

If you want to test it by yourself : http://sqlfiddle.com/#!2/ba2a1/16/0