MySQL user rank with sorted results - mysql

Question

I have the following mysql statement to bring back top 10 user data plus the data for the signed-in user (if the signed-in user is in the top 10 there'll only be 10 results total, otherwise there's 11)...
(SELECT user_id, points, amountLikes, amountComments
FROM all_scores_table
ORDER BY points desc, amountLikes desc, amountComments desc
LIMIT 0,10)
UNION
(SELECT user_id, points, amountLikes, amountComments
FROM all_scores_table
WHERE user_id = $session_user_id)
ORDER BY points desc, amountLikes desc, amountComments desc
The all_scores_table has exactly 1 row per user. I'm now trying to add rank information to the second query (e.g. if there's 11 rows, I want to know whether the session_user_id is 11th or 468th in the list).
I've read a bunch of similar posts but couldn't find an answer that seemed to apply to the way I've written my initial query by unioning sorted results - e.g. I can't just add a simple count of rows with points greater than my user, because if they're even I want to reference amountLikes, amountComments to find the true order.
I could of course do this in PHP with a second query, but am hoping someone notices an elegant way to achieve this in mysql alone

Answer 1

I would recommend not trying to be clever and use one query. Instead, just make two queries, one which finds the top ten and the other which finds the logged in user along with his numerical rank. For the first query, you can use what you already have:
SELECT
user_id, points, amountLikes, amountComments
FROM all_scores_table
ORDER BY points DESC, amountLikes DESC, amountComments DESC
LIMIT 10
As for assigning ranks, you can easily handle this in your PHP code when you are iterating over the result set. Just use a variable counter starting at 1.
To get the rank of the currently logged in user, it will take more work, because he could be buried in the midst of hundreds (or more) of records. One option is to use session variables:
SET #row_number = 0;
SELECT
(#row_number:=#row_number + 1) AS rank,
user_id, points, amountLikes, amountComments
FROM all_scores_table
WHERE user_id = $session_user_id
ORDER BY points DESC, amountLikes DESC, amountComments DESC
This second query should return a single record (assuming each user appears only once), containing the metadata you need along with a numerical rank.
In your PHP logic, you can check if the rank be in the top ten, and, if so, not display this extra single record on the bottom of your table.