Question

我正在处理以下查询，您会找到示例数据 on this db fiddle ：

SET @count=0; 
SELECT ( @rank := IF(@points = points, @rank + 1, IF(@points := points, @rank + 1, @rank + 1)) ) AS rank,
       er.* 
FROM (SELECT cc6_MensLeague_players.id AS `id`, 
             ( 1288 ) AS points, 
             (SELECT Max(@count := IF(outcome = 2, @count + 1, 0)) AS max_consecutive_wins 
              FROM (SELECT * 
                    FROM cc6_MensLeague_rounds 
                    WHERE player = 785 
                    ORDER BY date ASC) AS temp
              ) AS `maxcon` 
      FROM cc6_MensLeague_players 
      GROUP BY `id`) er 
CROSS JOIN (SELECT @rank := 0, @points := -1) params 
ORDER BY id DESC;

此代码运行完美（由于Tobias Thornfeldt Nissen），但是我现在想做的是使玩家ID（785）动态...我似乎无法传递我的ID变量（cc6_MensLeague_players.id）到子查询from子句。

我尝试了以下方法：

在@id :=的开头添加... cc6_mensleague_players.id AS id ...，并将... WHERE player = 785 ...更改为... WHERE player = @id ...，祝您好运！
将... player = 785 ORDER BY DATE ASC ...更改为... player = @id GROUP BY ID ORDER BY DATE ASC ...真幸运！
我也尝试了其他一些战术，但我只是想不通。

所以我的问题是：如何使WHERE player = cc6_mensleague_players.id（第9行）正常工作？

如果您能指出正确的方向，将不胜感激。

谢谢。

Answer 1

您可以将为子查询提供的别名用作id：

SET @count=0;

SELECT ( @rank := IF(@points = points, @rank + 1,
                  IF(
                  @points := points,
                           @rank + 1,
                                    @rank + 1)) )
       AS rank,
       er.*
FROM   (SELECT cc6_MensLeague_players.id
               AS
                      `id`,
               ( 1288 )
               AS
                      points,
               (SELECT Max(@count := IF(
                           outcome = 2,
                                     @count + 1,
                                     0)) AS
                       max_consecutive_wins
                FROM   (SELECT *
                        FROM
               cc6_MensLeague_rounds
                        WHERE  player = `id`
                        ORDER  BY date ASC) AS
                       temp) AS
                      `maxcon`
        FROM   cc6_MensLeague_players
        GROUP  BY `id`) er
       CROSS JOIN (SELECT @rank := 0,
                          @points := -1) params
ORDER  BY id DESC;

Answer 2

感谢您的回复：-）

我能够找出解决方案。没有你们所有人都做不到。

我最终从条款中删除了第二个括号

... FROM (SELECT * ... ) AS temp ...

和瞧-@id变量的作用就像一个魅力

这是最后的代码

set @id=0, @count=0; select ( @rank := if(@points = points, @rank + 1, if(@points := points, @rank + 1, @rank + 1)) ) as rank, er.* from (select @id := cc6_MensLeague_players.id as id , ( 1288 ) as points, (select max(@count := if(outcome = 2, @count + 1, 0)) as MaxWins from cc6_MensLeague_rounds where player = @id order by date asc ) as maxcon from cc6_MensLeague_players group by id ) er cross join (select @rank := 0, @points := -1) params order by id desc;

https://www.db-fiddle.com/f/35EQE2yzdxNs3KHZnQkMuQ/6

谢谢大家。

Mysql-将变量从子句传递给子查询

2 个答案: