从桌上锦标赛和最大赢家玩家中选择不同的列

Question

我搜索了一下，没有答案，我正在做一个练习，我有 4 张桌子

表“比赛作为t”

ID	NAME	CODE
1	Roland Garros	RG
2	Australian open	AO
3	US open	US
4	Wimbledon	WI

...

表“试用为e”

ID	YEAR	GENDER_TRIAL	ID_TOURNAMENT (fk_toTournament)
1	2010	Male	1
2	2010	Female	1
3	2011	Female	2
4	2011	Male	2
5	2011	Male	1

...

表格“match_tennis as mt”

ID	ID_trial (fk_toTrial)	ID_winner (fk_toPlayer)	ID_loser (fk_toPlayer)
1	2	1	2
2	3	3	1
3	1	2	3

...

表“玩家作为 p” |身份证 |姓名 |性别 | |:--:|:---------------:|:------:| | 1 |拉斐尔·纳达尔 |男 | | 2 |罗杰·费德勒 |男 | | 3 |塞雷娜·威廉姆斯 |女 | | 2 |威廉姆斯维纳斯 |女 |

...

所以我的表有很多记录，预期的结果是

ID (t.id)	Tournament (t.Name)	Code (t.Code)	Female Player with most wins (p.Name)	Wins (MAX(COUNT(WINNER)))	Male Player with most wins (p.Name)	Wins (MAX(COUNT(WINNER)))
1	Roland Garros	RG	Serena Williams	5	Rafael Nadal	7
2	Australian open	AO	Venus Williams	3	Roger Federer	9
3	US open	US	Simona Halep	7	Novak Djokovic	5
4	Wimbledon	WI	Wozniacki Caroline	3	Andy Murray	4

类似的东西......我无法更改我的数据库表，到目前为止，我得到了所有锦标赛以及每个玩家的所有胜利

我的查询是这样的

SELECT t.id, t.name, t.code, p.name, COUNT(*) as wins "
                + "FROM tournament t "
                + "INNER JOIN trial e ON e.id_tournament = t.id "
                + "INNER JOIN match_tennis mt ON mt.id_trial = e.id "
                + "INNER JOIN player p ON mt.id_winner = p.id "
                + "GROUP BY t.name, p.name "
                + "ORDER BY wins DESC";

我有这样的东西作为预期的输出

Answer 1

您需要首先考虑如何获得每个玩家/锦标赛组合的获胜次数。

SELECT t.id, t.name, t.code, e.gender_trial, p.name as player_name, COUNT(*) as wins
FROM tournament t INNER JOIN
     trial e
     ON e.id_tournament = t.id INNER JOIN
     match_tennis mt
     ON mt.id_trial = e.id INNER JOIN
     player p
     ON mt.id_winner = p.id
GROUP BY t.id, t.name, t.code, e.gender_trial, p.name;

这与您的查询非常相似，但GROUP BY 和SELECT 是一致的，并且还包括性别。

有了这个结果，你可以做两件事。第一个是按性别计算第一个。第二个是将每个锦标赛聚合成一行。所以：

WITH tp as (
      SELECT t.id, t.name, t.code, e.gender_trial, p.name, COUNT(*) as wins 
      FROM tournament t INNER JOIN
           trial e
           ON e.id_tournament = t.id INNER JOIN
           match_tennis mt
           ON mt.id_trial = e.id INNER JOIN
           player p
           ON mt.id_winner = p.id
      GROUP BY t.id, t.name, t.code, e.gender_trial, p.name
     )
SELECT t.id, t.name, t.code,
       MAX(CASE WHEN seqnum = 1 AND gender_trial = 'Female' THEN player_name END)) as female_first, 
       MAX(CASE WHEN seqnum = 1 AND gender_trial = 'Female' THEN wins END)) as female_wins,
       MAX(CASE WHEN seqnum = 1 AND gender_trial = 'Male' THEN player_name END)) as male_first, 
       MAX(CASE WHEN seqnum = 1 AND gender_trial = 'Male' THEN wins END)) as male_wins
FROM (SELECT tp.*,
             ROW_NUMBER() OVER (PARTITION BY id, gender_trial ORDER BY wins DESC) as seqnum
      FROM tp
     ) tp
GROUP BY t.id, t.name, t.code;