我有以下表格：计数连接表
Players
- id
- name
Games
- id
- game_type_id
- season_id
Goals
- player_id
- game_id
Assists
- player_id
- game_id
我一直努力试图建立一个查询/视图，这将使我的球员的目标，并协助计数每个赛季和游戏类型。每个球员都列出了每个赛季和游戏类型，无论他们是否有进球/助攻，这一点很重要。
该查询将用于创建视图。它可以在一个查询中完成吗？
更新：这是一个SQL Fiddle与一些生产样品数据。
修订
SELECT
players.id,
players.name,
games.season_id,
games.game_type_id,
sum(CASE WHEN g.goals IS NULL THEN 0 ELSE g.goals END) AS goals,
sum(CASE WHEN a.assists IS NULL THEN 0 ELSE a.assists END) AS assists
FROM players
CROSS JOIN games
LEFT JOIN (
SELECT
game_id, player_id,
count(*) AS goals
FROM goals
GROUP BY
game_id, player_id
) g ON
g.player_id = players.id
AND g.game_id = games.id
LEFT JOIN (
SELECT
game_id, player_id,
count(*) AS assists
FROM assists
GROUP BY
game_id, player_id
) a ON
a.player_id = players.id
AND a.game_id = games.id
GROUP BY
players.id,
players.name,
games.season_id,
games.game_type_id
这不是很短的版本，但它应该是现在。
我在查看数据时发现了一些不一致的情况。这是一个[示例数据集]（http://sqlfiddle.com/#!2/8312c/6）。你会发现从第一个查询和你的目标数不匹配。 –
@YanSarazin你是对的，这是我的错！它的根在第二个左连接 - 它克隆行。我认为第一个答案没有这个错误。 – pkuderov
您的更新似乎是赢家！ –
SELECT
players.id,
players.name,
games.season_id,
games.game_type_id,
SUM(COALESCE(assists.rows, 0)) AS assists,
SUM(COALESCE(goals.rows, 0)) AS goals
FROM
players
CROSS JOIN
games
LEFT JOIN
(SELECT game_id, player_id, COUNT(*) AS rows FROM assists GROUP BY game_id, player_id) AS assists
ON assists.game_id = games.game_id
LEFT JOIN
(SELECT game_id, player_id, COUNT(*) AS rows FROM goals GROUP BY game_id, player_id) AS assists
ON goals.game_id = games.game_id
GROUP BY
players.id,
players.name,
games.season_id,
games.game_type_id
但它可能会提高性能，如果你有一个Seasons表和GameType表。
SELECT
players.id,
players.name,
seasons.id,
game_types.id,
SUM(COALESCE(assists.rows, 0)) AS assists,
SUM(COALESCE(goals.rows, 0)) AS goals
FROM
players
CROSS JOIN
seasons
CROSS JOIN
game_types
LEFT JOIN
games
ON games.season_id = seasons.id
AND games.game_type = game_types.id
LEFT JOIN
(SELECT game_id, player_id, COUNT(*) AS rows FROM assists GROUP BY game_id, player_id) AS assists
ON assists.game_id = games.game_id
LEFT JOIN
(SELECT game_id, player_id, COUNT(*) AS rows FROM goals GROUP BY game_id, player_id) AS assists
ON goals.game_id = games.game_id
GROUP BY
players.id,
players.name,
seasons.id,
game_types.id
b！打败了我。左边的连接是不是也需要在'player_id'上？ – swasheck
不得不修复一些拼写错误以获得此查询运行，但计数都是关闭的。我用SQL小提琴更新了我的问题。 –
真棒，我没想到十字架的加盟，我想出了：
从玩家选择 players.id，games.game_type_id，games.season_id，GC，AC
左加入（select count（id）as c，player_id，game_id from players group by player_id，game_id）作为g.player_id = players.id上的g。
left join（select count（id）as c，player_id，game_id from由player_id，game_id组成的助攻组）作为a.player_id = players.id
right加入游戏games.id = g.game_id和games.id = a.game_id group by players.id，games.game_type_id，games.season_id;
试试这个：
select p.id,
p.name,
gm.season_id,
gm.game_type_id,
sum(gl.goalcount),
sum(a.AssistCount)
from players p
left join
(
select game_id, player_id, count(*) GoalCount
from goals
group by game_id, player_id
) gl
on p.id = gl.player_id
left join
(
select game_id, player_id, count(*) AssistCount
from assists
group by game_id, player_id
) a
on p.id = a.player_id
left join games gm
on gl.game_id = gm.id
and a.game_id = gm.id
where season_id is not null
group by p.id,
p.name,
gm.season_id,
gm.game_type_id
也似乎缺少一个表中有没有'GameType' – swasheck
的'GameType'表其实并不重要，因为我需要的是在“游戏”表中找到的游戏类型的ID。 我会尽量在SQL小提琴中弄点东西。 –
另外，“目标”和“助攻”都有一个缺失值（比如该球员在该游戏中的总进球数），或者如果球员有多个目标，您是否有多个“player_id”和“game_id”在一场比赛中？ – swasheck