两个表中两列的总和

Question

我有两个表，需要获取两列的总和（每张表中的一个）。

• 桌上游戏（id_tournament，id_game，电子邮件，积分）PK（id_tournament，id_game，电子邮件）
• 表结果（id_tournament，电子邮件，积分）PK（id_tournament，电子邮件）
• 表User（id_user，email，name）PK（id_user）

示例表结果：

1,me@hotmail.com,3 
1,you@hotmail.com,4

示例表游戏：

1,1,me@hotmail.com,5  
1,2,me@hotmail.com,3  
1,3,me@hotmail.com,2   
1,1,you@hotmail.com,4  
1,3,you@hotmail.com,2

示例表用户：

1,me@hotmail.com,John  
2,you@hotmail.com,Peter

我的输出应为：

John 13  
Peter 10

我尝试使用

SELECT t3.name, SUM(t1.points+t2.points) as Total 
FROM user t3, games t1, results t2 
WHERE  t1.email=t2.email AND t2.email=t3.email AND  t1.id_tournament=t2.tournament 
GROUP BY t1.email 
ORDER BY Total DESC

但是数字却很奇怪

Answer 1

从游戏表中获得总分，从结果表中分别获得总分，然后将它们合计。

像这样：

 SELECT v.name
      , SUM(v.points) AS points
   FROM (
          SELECT gu.name
               , SUM(g.points) AS points
            FROM games g
            JOIN user gu
              ON gu.email = g.email
           GROUP BY gu.name

           UNION ALL

          SELECT ru.name
               , SUM(r.points) AS points
            FROM results r
            JOIN user ru
              ON ru.email = r.email
           GROUP BY ru.name   
        ) v
    GROUP BY v.name
    ORDER BY v.name

编辑

添加了缺少的GROUP BY子句。

如果我们需要从用户表中返回名称的所有值，即使游戏或结果中没有相关的行也是如此...

 SELECT n.name
      , IFNULL(SUM(v.points),0) AS points
   FROM users n
   LEFT
   JOIN (
          SELECT gu.name
               , SUM(g.points) AS points
            FROM games g
            JOIN user gu
              ON gu.email = g.email
           GROUP BY gu.name

           UNION ALL

          SELECT ru.name
               , SUM(r.points) AS points
            FROM results r
            JOIN user ru
              ON ru.email = r.email
           GROUP BY ru.name   
        ) v
      ON v.name = n.name
    GROUP BY n.name
    ORDER BY n.name