帮助连接多个表的 SQL 查询

Question

首先我将解释这个情况，我有一个具有这样结构的表tbl_game。该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 保存每个玩家的得分。如果您想知道，这是一个基本的掷骰子游戏

|   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，id 这里是投掷 ID，而不是游戏 ID。这里，player_id 1 和 2 的每个玩家都掷了两次骰子，并获得了各自的得分，所有这些得分都在同一场比赛中显示，而在另一场比赛中只出现一次

现在，使用这两个表，我需要创建一条记录设置，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        |

我尝试了很多胡言乱语的查询，但没有给出正确的结果？ 对此的正确查询是什么？

更新

因为，大多数答案都受到以下事实的限制：player1id 和player2id 必须已知或固定。

因此，我即将提供的信息可能有助于消除困惑。 还有另外一个表，保存着玩家的信息。 tbl_pupil 结构如下所示

|   id    |   unique_id   | name     |
|---------+---------------+----------|
|   1     |     001       | some     |
|   2     |     002       | another  |

，这些播放器统称为另一个表中的一对 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             |

现在我只是显示结果顺便说一下，一个游戏ID。我没有保存足够的知识，无法将上述记录分组为一个，其中玩家1单独的得分总和在一列中，玩家2单独的得分总和在另一列中。

Answer 1

试试这个：

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

Answer 2

这与其他一些答案类似，但关键不依赖于玩家 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，我概括了上述内容以允许更多 > > 2名玩家：

2个CTE表仅显示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

Answer 3

您需要内部连接两个表，并汇总您的分数。要执行基本的枢轴，您需要在我使用 CASE 语句按玩家进行聚合之后进行。

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

Answer 4

我认为这应该可以完成你想做的事情。

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

Answer 5

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