跨多个表求和值

Question

我在尝试对两个不同表中的一个公共用户 ID 分组的字段求和时遇到问题。

为您提供更多信息...我正在尝试按日期跟踪球员的表现（即：所有 11 月 14 日得分最高的分数）。数据库是分开的，一张用于常规赛，一张用于季后赛。因此，例如，一名球员可能在 2001 年 5 月 3 日打了一场常规赛……但在 2005 年 5 月 3 日打了季后赛。

所以，我正在尝试构建一个包含所有日期每个玩家总和的视图。

一张桌子我有什么：

SELECT PlayerId,sum(Points) as TOT_PTS 
FROM RS_games 
WHERE DAY(Date)=$cur_day 
  AND MONTH(Date)=$cur_month 
GROUP BY PlayerId

...但我不知道如何在不创建第三个视图作为“垫脚石”的情况下将两个表中每个玩家的值相加。 有什么想法吗？

Answer 1

如果你想在（DAY-MONTH）之前得到结果，你可以这样做：

SELECT playerID, 
       CONCAT (DAY(DATE), '-', MONTH(DATE)) AS DAY_MONTH, 
       SUM(points) AS Total_Points
FROM (
  SELECT playerID, DATE, points
  FROM rs_games  
  UNION ALL  
  SELECT playerID, DATE, points
  FROM po_games
  ) a
GROUP BY 1, 2

sqlfiddle demo

这样，您最终会得到一个包含每个 playerId、dd-mm 的结果，以及这些年来特定日期得分的总和。

Answer 2

只是为了说明我在说什么：

select
  ALL_players.PlayerID as PlayerID
  COALESCE(reg.Points, 0) + COALESCE(po.Points, 0) as Points
from
ALL_players
left join
(select PlayerID, DATE(Date) as Date, sum(Points) as Points 
 from RS_games
 WHERE DAY(Date)=$cur_day AND MONTH(Date)=$cur_month
 group by PlayerID) as reg
on reg.PlayerID = ALL_players.PlayerID
left join
(select PlayerID, DATE(Date) as Date, sum(Points) as Points 
 from PO_games group by DATE(Date), PlayerID
 WHERE DAY(Date)=$cur_day AND MONTH(Date)=$cur_month
 group by PlayerID) as po
on po.PlayerID = ALL_players.PlayerID

编辑：再次查看要求，这将需要一个完整的外部连接或一些调整...调整（现在应该可以工作）