Mysql的查詢 - 與由組和max時間戳

Question

我試圖通過最大的時間標記的量的重量爲每個辦公桌

計算每個播放器中的量的加權平均值例如爲下列加權平均表：

 desk | player  | amount   | weight  | timestamp 
----------------------------------- 
---- 1 --- | ---- 1 --- | ---------2------|-----10-------|13:00 
---- 1 --- | ---- 1 --- | ---------1------|-----15-------|14:00 
---- 2 --- | ---- 1 --- | ---------5------|-----20-------|13:00 
---- 2 --- | ---- 1 --- | ---------3------|-----5-------|15:00 
---- 3 --- | ---- 2 --- | ---------5------|-----6-------|13:00 
---- 3 --- | ---- 2 --- | ---------2------|-----30-------|14:00 
---- 4 --- | ---- 2 --- | ---------1------|-----10-------|15:00 
---- 4 --- | ---- 2 --- | ---------6------|-----3-------|13:00 

的結果應該是：

**player | weigtedAmount** 
---1---| 1.5 ((15/20)*1 + (5/20)*3) 
---2---| 1.75 ((30/40)*2 + (10/40)*1) 

我嘗試下面的查詢，但我認爲我缺少一些時間戳= MAX（時間戳）地方：

select player,SUM(lates_data.amount * (lates_data.weight/ lates_data.sumWeight)) 
from (SELECT * 
     FROM (select player as plr, SUM(weight) as sumWeight 
      from playersDb.player_stats 
      group by plr 
      ) t1 INNER JOIN 
      (select desk, player, amount, weight 
      from playersDb.player_stats 
      group by desk, player 
      ) t2 
      ON t1.plr= t2.player 
    ) lates_data 
group by player 

任何想法？

拉茲

Answer 1

下面是一些代碼，應出示您需要的結果。

#DROP TABLE IF EXISTS deskWeight; 

CREATE TABLE deskWeight (desk INT UNSIGNED, player INT UNSIGNED, amount INT UNSIGNED, weight INT UNSIGNED, `timestamp` TIME); 

INSERT INTO deskWeight VALUES 
    (1, 1, 2, 10, '13:00'), 
    (1, 1, 1, 15, '14:00'), 
    (2, 1, 5, 20, '13:00'), 
    (2, 1, 3, 5, '15:00'), 
    (3, 2, 5, 6, '13:00'), 
    (3, 2, 2, 30, '14:00'), 
    (4, 2, 1, 10, '15:00'), 
    (4, 2, 6, 3, '13:00'); 

SELECT A.player, SUM(A.weight/B.weightSum * A.amount) weightedAmount FROM 
    (
    SELECT A.player, B.weight, B.amount FROM 
     (
     SELECT desk, player, MAX(`timestamp`) timestampMax FROM deskWeight GROUP BY desk, player 
     ) A 
    INNER JOIN 
     deskWeight B 
    ON A.desk = B.desk AND A.player = B.player AND A.timestampMax = B.`timestamp` 
    ) A 
INNER JOIN 
    (
    SELECT A.player, SUM(B.weight) weightSum FROM 
     (
     SELECT desk, player, MAX(`timestamp`) timestampMax FROM deskWeight GROUP BY desk, player 
     ) A 
    INNER JOIN 
     deskWeight B 
    ON A.desk = B.desk AND A.player = B.player AND A.timestampMax = B.`timestamp` 
    GROUP BY A.player 
    ) B 
ON A.player = B.player 
GROUP BY player; 

問候，

詹姆斯

Answer 2

謝謝！

我設法與此查詢做到這一點：

SELECT player, sum(aw)/sum(weight) as total, sum(weight) as weight, max(timestamp) as timestamp FROM 
    (
     SELECT player, desk, amount*weight as aw, weight, timestamp FROM 
     (
      (SELECT player as p1, desk as d1, max(timestamp) as maxTs FROM playersDb.player_stats group by player, desk) mts 
      inner join 
      (SELECT * FROM playersDb.player_stats) data 
     on data.player = mts.p1 and data.desk = mts.d1 and data.timestamp = mts.maxTs 
     ) 
    ) t 
group by player 

拉茲