MySQL - query for sorting - mysql

Question

Example data:
username score time
-------- ----- ----
jim 90 50
jim 90 30
paul 50 30
bob 100 90
tim 90 20
I want to be able to sort by score in descending order. If two scores are the same, sort by the lowest time. If there are multiple rows with the same username, I only want one. So the above table should look like this:
username score time
-------- ----- ----
bob 100 90
tim 90 20
jim 90 30
paul 50 30
I have a query that nearly produces this, however, if the scores are the same, it doesn't sort by lowest time. How would I do this?
SELECT U.username, S.score, S.time
FROM scores S JOIN users U ON S.user_id=U.user_id
WHERE NOT EXISTS (
SELECT 1 FROM scores R2 WHERE R2.user_id = S.user_id and R2.score_id > S.score_id
)
AND test_id=0
AND module_id=1
ORDER BY score DESC, time ASC;

Answer 1

Avoiding using a sub query and using a LEFT OUTER JOIN instead.:-
SELECT U.username, s1.score, s1.time
FROM scores s1
INNER JOIN users U
ON s1.user_id = U.user_id
LEFT OUTER JOIN scores s2
ON s1.user_id = s2.user_id
AND (s1.score < s2.score
OR (s1.score = s2.score
AND s1.time > s2.time))
WHERE s2.user_id IS NULL
ORDER BY s1.score DESC, s1.time ASC
This does a LEFT OUTER JOIN against the score table looking for a match for the same user with a higher score, or the same score and a faster time. Any where these are found are not the best score so are dropped with the WHERE clause
SQL fiddle for this:-
http://sqlfiddle.com/#!2/7f3e93/3
Edit - adding the test_id and module_id checks if required:-
SELECT U.username, s1.score, s1.time
FROM scores s1
INNER JOIN users U
ON s1.user_id = U.user_id
LEFT OUTER JOIN scores s2
ON s1.user_id = s2.user_id
AND s2.test_id = 0
AND s2.module_id = 1
AND (s1.score < s2.score
OR (s1.score = s2.score
AND s1.time > s2.time))
WHERE s2.user_id IS NULL
AND s1.test_id = 0
AND s1.module_id = 1
ORDER BY s1.score DESC, s1.time ASC

Answer 2

SELECT U.username, max(S.score) as maxscore, min(S.time) as mintime
FROM scores S
JOIN users U ON S.user_id=U.user_id
WHERE NOT EXISTS
(
SELECT 1 FROM scores R2
WHERE R2.user_id = S.user_id and R2.score_id > S.score_id
)
AND test_id=0
AND module_id=1
GROUP BY U.username
ORDER BY maxscore DESC, mintime ASC;