从在一场比赛中主场进球最多的球队中选择英格兰球员的人数

Question

团队

ID	TEAM_NAME
1	Arsenal

比赛

ID	DATE	HOME_TEAM_ID	AWAY_TEAM_ID	HOME_SCORE	AWAY_SCORE
1	2018-08-10	10	7	2	1

国家

ID	NATION_NAME
1	Spain

玩家

ID	NAME	NATION_ID	TEAM_ID
100	David de Gea	1	10

目标

GOAL_ID	MATCH_ID	PLAYER_ID	GOAL_ORDER	OWN_GOAL
1	1	106	1	False

我试图从上面的数据库（SQL Server）中计算出主场进球最多的球队的英格兰球员人数。

我的查询：

SELECT TOP 1 COUNT(PLAYER.PLAYER_ID), MAX(HOME_SCORE)
FROM PLAYER 
JOIN NATION ON PLAYER.NATION_ID = NATION.NATION_ID
JOIN MATCH ON MATCH.HOME_TEAM_ID = PLAYER.TEAM_ID
WHERE NATION.NATION_NAME = 'England'
GROUP BY PLAYER.PLAYER_ID
ORDER BY MAX(MATCH.HOME_SCORE) DESC

它给出了max(home_score) 的正确答案，但该队的英国球员人数不正确。

Answer 1

只是未经测试的记事本涂鸦。
因为没有样本数据我无法验证。

SELECT TOP 1
  match.match_id
, match.home_score
, COUNT(CASE 
        WHEN player_nation.nation_name = 'England'
        THEN player.player_id
        END) AS EnglishPlayers
, COUNT(goal.goal_id) AS TotalGoals
FROM GOAL AS goal
JOIN PLAYER AS player 
  ON player.player_id = goal.player_id
JOIN MATCH AS match 
  ON match.match_id = goal.match_id
 AND match.home_team_id = player.team_id
LEFT JOIN NATION AS player_nation 
  ON player_nation.nation_id = player.nation_id
GROUP BY match.match_id
ORDER BY TotalGoals DESC

Answer 2

你需要先获得得分最高的团队，然后左加入NATION到PLAYER，然后统计非空NATION_ID的数量。

您还按错误的值分组

SELECT TOP (1)
  p.TEAM_ID,
  NumPlayers = COUNT(*),
  NumEnglishPlayers = COUNT(n.NATION_ID),
  HighestScore = m.HOME_SCORE
FROM (
    SELECT TOP (1) *
    FROM MATCH m
    ORDER BY
      m.HOME_SCORE DESC
) m
JOIN PLAYER p ON m.HOME_TEAM_ID = p.TEAM_ID
LEFT JOIN NATION n ON p.NATION_ID = n.NATION_ID
    AND n.NATION_NAME = 'England'
GROUP BY
  m.HOME_TEAM_ID,
  m.HOME_SCORE;

db<>fiddle