Exclude users with zero score from ranking - mysql

Question

I've come across this great solution to rank users based on their score in mysql.
SELECT d.*, c.ranks
FROM
(
SELECT Score, #rank:=#rank+1 Ranks
FROM
(
SELECT DISTINCT Score
FROM tableName a
ORDER BY score DESC
) t, (SELECT #rank:= 0) r
) c
INNER JOIN tableName d
ON c.score = d.score
However, I would like to know if there is a way to exclude users with 0 or without score from the ranking, but still return these users in the results.
So for example
KEY username password score Ranks
1 Anna 123 8 1
2 Bobby 345 5 2
3 Helen 678 5 2
4 Jon 567 -2 3
5 Arthur ddd -9 4
4 Chris 444 0
5 Liz eee 0

Answer 1

Since you want to SELECT all of your users, start with that:
SELECT
user.*
FROM user
Now, we want to add in a table of ranked users, so we'll start to add in complexity. We're aiming to get a temporary table of ranked users, so we'll LEFT JOIN as to not filter out any non-ranked users.
SELECT
user.*,
ranked_user.score,
ranked_user.rank
FROM user
LEFT JOIN(
// subquery
) AS ranked_user ON ranked_user.user_id = user.id
Then we'll have to figure out the section for the subquery where the ranks are determined. You have most of it already, I'm just going to add in an IF statement to only assign a rank if they have a score. Altogether, you get this:
SELECT
user.*,
ranked_user.score,
ranked_user.rank
FROM user
LEFT JOIN(
SELECT
score,
user_id,
IF(score = 0 OR score IS NULL, null, #rank:=#rank+1) AS rank
FROM(
SELECT
DISTINCT score,
user_id
FROM stat
ORDER BY score DESC
) t, (SELECT #rank:= 0) r
) ranked_user ON ranked_user.user_id = user.user_id
Here's how that IF statement works:
IF(score = 0 OR score IS NULL,
# if c.score is 0 or missing
null,
# set the value to null
#rank:=#rank+1)
# otherwise, calculate a rank
AS rank
# call this value "rank"
Just a side note: I'd change user.* and actually list each column of user that you want. That's considered best practice.