php/mysql - 计数和分组

Question

我有一个包含已玩游戏及其得分的数据库。现在我想运行一个查询，计算每支总进球数超过 x 的球队的所有结果（主客场加起来）。

数据库结构：

+----------+----------+---------------+---------------+
| HomeTeam | AwayTeam | HomeTeamGoals | AwayTeamGoals |
+----------+----------+---------------+---------------+
| team1    | team2    |             3 |             1 |
| team3    | team4    |             1 |             2 |
| team1    | team3    |             4 |             4 |
| team4    | team2    |             0 |             1 |
+----------+----------+---------------+---------------+

想要的结果：

+-------+----------+--------------------+
| team  | played   |  games > 3.5 goals |
+-------+----------+--------------------+
| team1 |        2 |                  2 |
| team2 |        2 |                  1 |
| team3 |        2 |                  1 |
| team4 |        2 |                  0 |
+-------+----------+--------------------+

我在看这样的东西：

SELECT *, COUNT(*) AS total FROM games WHERE homeTeamGoals + awayTeamGoals > 3.5 GROUP BY homeTeam

但这仅适用于主场比赛，所以我需要一种方法来添加客场比赛。

Answer 1

• 分别以HomeTeam 和AwayTeam 为团队获取结果。
• 使用UNION ALL 组合结果
• 将结果用作Derived Table。
• 在团队的派生表上Group by，以获得结果。

尝试以下方法 (SQL Fiddle DEMO)：

SELECT derived_t.team, 
       SUM(derived_t.played) AS played, 
       SUM(derived_t.games)  AS 'games > 3.5 goals'
FROM 
(
  SELECT t1.HomeTeam as team, 
         COUNT(*) AS played, 
         SUM( IF(t1.HomeTeamGoals + t1.AwayTeamGoals > 3.5, 1, 0) ) AS games  
  FROM your_table AS t1 
  GROUP BY t1.HomeTeam

  UNION ALL 

  SELECT t1.AwayTeam as team, 
         COUNT(*) AS played, 
         SUM( IF(t1.HomeTeamGoals + t1.AwayTeamGoals > 3.5, 1, 0) ) AS games  
  FROM your_table AS t1 
  GROUP BY t1.AwayTeam
) AS derived_t
GROUP BY derived_t.team