Question

I have a table which records users’s scores at a game (a user may submit 5,10,20,as many scores as he wants).
I need to show the 20 top scores of a game, but per user. (as a user may have submitted eg 4 scores which are the top according to other users’s scores)
The query i have written is:

SELECT DISTINCT
    `table_highscores`.`userkey`,
    max(`table_highscores`.`score`),
    `table_users`.`username`,
    `table_highscores`.`dateachieved` 
FROM
    `table_highscores`, `table_users` 
WHERE
    `table_highscores`.`userkey` = `table_users`.`userkey`
AND
    `table_highscores`.`gamekey` = $gamekey  
GROUP BY
    `userkey` 
ORDER BY
    max(`table_highscores`.`score`) DESC,
LIMIT 0, 20;

The output result is ok, but there is a problem. When i calculate the difference of days (today-this of dateachieved) the result is wrong. (eg instead of saying “the score was submitted 22 days ago, it says 43 days ago) So,I have to do a second query for each score so to find the true date (meaning +20 queries). Is there any shorter way to find the correct date?
Thanks.

Answer 1

In your query you should use an explicit JOIN and you don’t need the DISTINCT keyword.

This query should solve your problem. I am assuming here that it is possible for a user to submit the same highscore more than once on different dates, and if that happens then you want the oldest date:

SELECT T1.userkey, T1.score, username, dateachieved FROM (
    (SELECT userkey, max(score) AS score
    FROM table_highscores
    WHERE gamekey = $gamekey
    GROUP BY userkey) AS T1
    JOIN
    (SELECT userkey, score, min(dateachieved) as dateachieved
    FROM table_highscores
    WHERE gamekey = $gamekey
    GROUP BY userkey, score) AS T2
    ON T1.userkey = T2.userkey AND T1.score = T2.score
) JOIN table_users ON T1.userkey = table_users.userkey
LIMIT 20