[英]Help with a SQL query joining multiple tables
首先我将解释这个案例,我有一个表tbl_game
具有这样的结构。 此表包含游戏开始的时间和配对玩游戏的时间
| id | time | pair_id |
-----------+--------------+ ---------------
1 | 123123123 | 1 |
2 | 123168877 | 1 |
我还有另一个表tbl_throws
保存每个玩家的分数。 如果您想知道, this a basic dice rolling game
| id | game_id | player_id | score |
-----------+--------------+---------------+---------|
| 1 | 1 | 1 | 2 |
| 2 | 1 | 2 | 5 |
| 3 | 1 | 1 | 9 |
| 4 | 1 | 2 | 11 |
| 5 | 2 | 1 | 7 |
| 6 | 2 | 2 | 6 |
现在,这里的id
是投掷 id,而不是游戏 id。 在这里, player_id
为 1 和 2 的每个玩家都掷了两次骰子,并得到了在同一场比赛中给出的相应分数,而在另一场比赛中只有一次
现在,使用这两个表,我需要创建一个记录集,即每个玩家在一场比赛中的总得分
| game_id | game_time | player1_total | player2_total|
|------------+-----------+---------------+--------------|
| 1 | 123123123 | 11 | 16 |
| 2 | 123168877 | 7 | 6 |
我尝试了很多 mumbo jumbo 查询,但没有给出正确的结果? 对此的正确查询是什么?
因为,大多数答案都受到一个事实的限制,即 player1id 和 player2id 必须是已知的或固定的。
因此,我即将提供的信息可能有助于消除混乱。 还有另一个表,其中保存了玩家的信息。 tbl_pupil
结构如下
| id | unique_id | name |
|---------+---------------+----------|
| 1 | 001 | some |
| 2 | 002 | another |
而这些玩家统称为,另一张表中的一对tbl_pair
| id | player1 | player2 |
|---------+---------------+----------|
| 1 | 1 | 2 |
So, now
select
g.id
g.time
p1.id as player1id
p1.name as player1name
t.score as player1score
p2.id as player2id
p2.name as player2name
t.score as player2score
FROM
tbl_game g,
inner join tbl_pair as pair on g.pair_id = pair.id
inner join tbl_pupil as p1 on p1.id = pair.player1
inner join tbl_pupil as p2 on p2.id = pair.player2
inner join tbl_throw as t on g.id = t.game_id
这是我的初步查询,它以这样的方式带来了记录集
| id | time | player1id | player1name | player1score | player2id | player2name | player2score |
----------------------------------------------------------------------------------------------------------------------------
| 1 | 12 | 1 | some | 5 | 2 | another | 2 |
| 1 | 12 | 1 | some | 5 | 2 | another | 5 |
| 1 | 12 | 1 | some | 9 | 2 | another | 9 |
| 1 | 12 | 1 | some | 11 | 2 | another | 11 |
现在我只是顺便显示一个游戏 id 的结果。 我没有保存足够的知识,将上述记录分组为一个,其中 player1 单独的总分在一列中,而 playe2 的单独总分总和在另一列中。
尝试这个:
SELECT
tbl_game.id AS game_id,
tbl_game.time AS game_time,
SUM(CASE WHEN player_id = 1 THEN score ELSE 0 END) AS player1_total,
SUM(CASE WHEN player_id = 2 THEN score ELSE 0 END) AS player2_total
FROM tbl_game JOIN tbl_thorws ON tbl_game.id = tbl_throws.game_id
GROUP BY tbl_game.id
您需要内部连接这两个表,并汇总您的分数。 要做基本的 pivot,你是在我使用CASE
语句按播放器聚合之后。
SELECT G.Id as Game_Id,
G.time as Game_Time,
SUM(CASE WHEN t.Player_id = 1 THEN t.score ELSE 0 END) as Player1_total,
SUM(CASE WHEN t.Player_id = 2 THEN t.score ELSE 0 END) as Player2_total
FROM tbl_game G
INNER JOIN tbl_throws T
ON g.id = t.game_id
GROUP BY g.ID, g.time
这与其他一些答案类似,但关键不取决于玩家 ID 为 1 和 2。
select
game_id = g.id,
game_time = g.time,
player1_total = SUM(case t.player_id when p.player1_id then t.score else 0 end),
player2_total = SUM(case t.player_id when p.player2_id then t.score else 0 end)
from
tbl_game g
join tbl_throws t on g.id = t.game_id
join ( --Get the player IDs for this game
select
game_id,
player1_id = MIN(player_id),
player2_id = MAX(player_id)
from
tbl_throws
group by game_id
) p
on p.game_id = t.game_id
group by
g.id, g.time
只是为了好玩,我将上述内容概括为允许更多 > 2 名玩家:
2 个 CTE 表只显示了我正在使用的测试数据
;WITH tbl_game as (
select ID = 1, time = 123123123, pair_id = 1
union select ID = 2, time = 123168877, pair_id = 1
),
tbl_throws as (
select id = 1, game_id = 1, player_id = 1, score = 2
union select id = 2, game_id = 1, player_id = 2, score = 5
union select id = 2, game_id = 1, player_id = 3, score = 5
union select id = 3, game_id = 1, player_id = 1, score = 9
union select id = 4, game_id = 1, player_id = 2, score = 11
union select id = 5, game_id = 2, player_id = 1, score = 7
union select id = 6, game_id = 2, player_id = 2, score = 6
)
select
game_id = g.id,
game_time = g.time,
player1_id = MAX(case x.player_no when 1 then t.player_id else 0 end),
player1_total = SUM(case x.player_no when 1 then t.score else 0 end),
player1_id = MAX(case x.player_no when 2 then t.player_id else 0 end),
player2_total = SUM(case x.player_no when 2 then t.score else 0 end),
player3_id = MAX(case x.player_no when 3 then t.player_id else 0 end),
player3_total = SUM(case x.player_no when 3 then t.score else 0 end),
player4_id = MAX(case x.player_no when 4 then t.player_id else 0 end),
player4_total = SUM(case x.player_no when 4 then t.score else 0 end)
/* Add more rows for the number of players permitted in a single game */
from
tbl_game g
join tbl_throws t on g.id = t.game_id
cross apply (
select player_no = COUNT(distinct player_id)
from tbl_throws sub
where sub.player_id <= t.player_id
and Sub.game_id = t.game_id
) x
group by
g.id, g.time
我认为这应该做你想做的事情。
SELECT
tbl_game.id as game_id,
tbl_game.time as game_time,
SUM(player1.score) as player1_total,
SUM(player2.score) as player2_total
FROM tbl_game
INNER JOIN tbl_throws player1 ON player1.game_id = tbl_game.id AND player1.player_id = 1
INNER JOIN tbl_throws player2 ON player2.game_id = tbl_game.id AND player2.player_id = 2
GROUP BY tbl_game.id, tbl_game.time
SELECT t.game_id
, t.game_time
, ( SELECT SUM(t.score)
FROM tbl_throws AS t
WHERE t.game_id = g.id
AND player_id = 1
) AS player1_total
, ( SELECT SUM(t.score)
FROM tbl_throws AS t
WHERE t.game_id = g.id
AND player_id = 2
) AS player2_total
FROM tbl_game AS g
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