querying for user's ranking in one-to-many tables
I am trying to write a query to find the score rank of a user's games. I need it to take in a user id and the开发者_运维百科n return that user's relative ranking to other user's scores. There is a user and a game table. The game table has a userId field with a one-to-many relationship.
Sample table:
users:
id freebee 1 10 2 13games:
userId score 1 15 1 20 2 10 1 15
passing $id 1 into this function should return the value 1, as user 1 currently has the highest score. Likewise, user 2 would return 2.
Currently this is what I have:
SELECT outerU.id, (
SELECT COUNT( * )
FROM users userI, games gameI
WHERE userI.id = gameI.userId
AND userO.id = gameO.userId
AND (
userI.freebee + SUM(gameI.score)
) >= ( userO.freebee + SUM(gameO.score) )
) AS rank
FROM users userO,
games gameO
WHERE id = $id
Which is giving me an "invalid use of group function" error. Any ideas?
SELECT u.id,total_score,
( SELECT COUNT(*) FROM
(SELECT u1.id, (IFNULL(u1.freebee,0)+ IFNULL(SUM(score),0)) as total_score
FROM users u1
LEFT JOIN games g ON (g.userId = u1.id)
GROUP BY u1.id
)x1
WHERE x1.total_score > x.total_score
)+1 as rank,
( SELECT COUNT(DISTINCT total_score) FROM
(SELECT u1.id, (IFNULL(u1.freebee,0)+ IFNULL(SUM(score),0)) as total_score
FROM users u1
LEFT JOIN games g ON (g.userId_Id = u1.id)
GROUP BY u1.id
)x1
WHERE x1.total_score > x.total_score
)+1 as dns_rank
FROM users u
LEFT JOIN
( SELECT u1.id, (IFNULL(u1.freebee,0)+ IFNULL(SUM(score),0)) as total_score
FROM users u1
LEFT JOIN games g ON (g.userId = u1.id)
GROUP BY u1.id
)x ON (x.id = u.id)
rank
- (normal rank - e.g. - 1,2,2,4,5), dns_rank
- dense rank (1,2,2,3,4). Column total_score
- just for debugging...
The query does not like the reference of an outer table in the Sum function SUM(gameO.score)
in the correlated subquery. Second, stop using the comma format for joins. Instead use the ANSI syntax of JOIN. For example, in your outer query did you really mean to use a cross join? That is how you wrote and how I represented it in the solution below but I doubt that is what you want.
EDIT
I've adjusted my query given your new information.
Select U.id, U.freebee, GameRanks.Score, GameRanks.Rank
From users As U
Join (
Select G.userid, G.score
, (
Select Count(*)
From Games As G2
Where G2.userid = G.userid
And G2.Score > G.Score
) + 1 As Rank
From Games As G
) As GameRanks
On GameRanks.userid = U.id
Where U.id =1
I'm not a MySQL person, but I believe that the usual way to do ranking in it is using a variable within your SQL statement. Something like the below (untested):
SELECT
SQ.user_id,
@rank:=@rank + 1 AS rank
FROM
(
SELECT
U.user_id,
U.freebee + SUM(COALESCE(G.score, 0)) AS total_score
FROM
Users U
LEFT OUTER JOIN Games G ON
G.user_id = U.user_id
) SQ
ORDER BY
SQ.total_score DESC
You could use that as a subquery to get the rank for a single user, although performance-wise that might not be the best route.
Here is "simplified" version for calculating a rank based only on "games" table. For calculating rank for a specific game only you need to add additional joins.
SELECT COUNT(*) + 1 AS rank
FROM (SELECT userid,
SUM(score) AS total
FROM games
GROUP BY userid
ORDER BY total DESC) AS gamescore
WHERE gamescore.total > (SELECT SUM(score)
FROM games
WHERE userid = 1)
It's based on the idea that ranking
== number of players with bigger score
+ 1
Check this out: http://rpbouman.blogspot.com/2009/09/mysql-another-ranking-trick.html
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