我有以下表格：計數連接表
Players
- id
- name
Games
- id
- game_type_id
- season_id
Goals
- player_id
- game_id
Assists
- player_id
- game_id
我一直努力試圖建立一個查詢/視圖，這將使我的球員的目標，並協助計數每個賽季和遊戲類型。每個球員都列出了每個賽季和遊戲類型，無論他們是否有進球/助攻，這一點很重要。
該查詢將用於創建視圖。它可以在一個查詢中完成嗎？
更新：這是一個SQL Fiddle與一些生產樣品數據。
修訂
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
這不是很短的版本，但它應該是現在。
我在查看數據時發現了一些不一致的情況。這是一個[示例數據集]（http://sqlfiddle.com/#!2/8312c/6）。你會發現從第一個查詢和你的目標數不匹配。 –
@YanSarazin你是對的，這是我的錯！它的根在第二個左連接 - 它克隆行。我認爲第一個答案沒有這個錯誤。 – pkuderov
您的更新似乎是贏家！ –
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
但它可能會提高性能，如果你有一個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！打敗了我。左邊的連接是不是也需要在'player_id'上？ – swasheck
不得不修復一些拼寫錯誤以獲得此查詢運行，但計數都是關閉的。我用SQL小提琴更新了我的問題。 –
真棒，我沒想到十字架的加盟，我想出了：
從玩家選擇 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）作爲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組成的助攻組）作爲a.player_id = players.id
right加入遊戲games.id = g.game_id和games.id = a.game_id group by players.id，games.game_type_id，games.season_id;
試試這個：
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
也似乎缺少一個表中有沒有'GameType' – swasheck
的'GameType'表其實並不重要，因爲我需要的是在「遊戲」表中找到的遊戲類型的ID。 我會盡量在SQL小提琴中弄點東西。 –
另外，「目標」和「助攻」都有一個缺失值（比如該球員在該遊戲中的總進球數），或者如果球員有多個目標，您是否有多個「player_id」和「game_id」在一場比賽中？ – swasheck