如何在mysql中动态地将行旋转到列

Question

我遇到了一个问题，我认为我必须使用 pivot 来解决我不熟悉的问题。 如果有人能为我提供帮助，我将非常感激。

以下查询产生以下输出。 这当然是正确的。

SELECT tm.team_id AS team, pp.user_name AS name, tm.rank AS rank
FROM teams_members AS tm 
    LEFT JOIN players_profiles AS pp
    ON pp.uid=tm.user_id
WHERE tm.team_id = 1 OR tm.team_id = 2
ORDER BY  tm.team_id, tm.rank

team	name	rank
1	1Player1	1
1	1Player2	2
1	1Player3	2
1	1Player4	2
1	1Player5	3
1	1Player6	4
1	1Player7	5
2	2Player1	1
2	2Player2	2
2	2Player3	2
2	2Player4	2

我希望桌子看起来像这样。我如何调整查询？ 有可能，等级2可以容纳无限数量的玩家。等级 1、3、4 和 5 被设置为限制为 1。

team	1	2	2	2	3	4	5
1	1Player1	1Player2	1Player3	1Player4	1Player5	1Player6	1Player7
2	2Player1	2Player2	2Player3	2Player4
3	3Player1	3Player2	3Player3	3Player4			3Player5
4	4Player1	4Player2			4Player3		3Player4

感谢您的帮助。非常感谢！

Answer 1

再举一个例子： DBFIDDLE

DROP TABLE IF EXISTS testPivot ;
CREATE TABLE testPivot(i int, name varchar(20), k int);

INSERT INTO testPivot VALUES
   (1,'1Player1',1),
   (1,'1Player2',2),
   (1,'1Player3',2),
   (1,'1Player4',2),
   (1,'1Player5',3),
   (1,'1Player6',4),
   (1,'1Player7',5),
   (2,'2Player1',1),
   (2,'2Player2',2),
   (2,'2Player3',2),
   (2,'2Player4',2);
   
   
SELECT
  i as team,
  max(case when right(name,1)='1' then name else '' end) as '1',
  max(case when right(name,1)='2' then name else '' end) as '2',
  max(case when right(name,1)='3' then name else '' end) as '3',
  max(case when right(name,1)='4' then name else '' end) as '4',
  max(case when right(name,1)='5' then name else '' end) as '5',
  max(case when right(name,1)='6' then name else '' end) as '6',
  max(case when right(name,1)='7' then name else '' end) as '7'
FROM testPivot
GROUP BY i;

输出：

team	1	2	3	4	5	6	7
1	1Player1	1Player2	1Player3	1Player4	1Player5	1Player6	1Player7
2	2Player1	2Player2	2Player3	2Player4

编辑：在 1 列中获取组 2（我只应用了 rank==2 的更改），使用：

SELECT
  i as team,
  max(case when right(name,1)='1' then name else '' end) as '1',
  regexp_replace(regexp_replace(regexp_replace(group_concat(case when k=2 then name else '' end),'[,]+',','),'^,',''),',$','') as '2',
  -- max(case when right(name,1)='2' then name else '' end) as '2',
  max(case when right(name,1)='3' then name else '' end) as '3',
  max(case when right(name,1)='4' then name else '' end) as '4',
  max(case when right(name,1)='5' then name else '' end) as '5',
  max(case when right(name,1)='6' then name else '' end) as '6',
  max(case when right(name,1)='7' then name else '' end) as '7'
FROM testPivot
GROUP BY i;

team	1	2	3	4	5	6	7
1	1Player1	1Player2,1Player3,1Player4	1Player3	1Player4	1Player5	1Player6	1Player7
2	2Player1	2Player2,2Player3,2Player4	2Player3	2Player4

Answer 2

MySQL 不支持 PIVOT 关系运算符。但肯定有办法在 MySQL 中透视数据。您数据中的挑战是数据透视列的非唯一性。您的输出中会有多个名称为“2”的列。

所以我通过在名称字段的最后三个后面连接团队来创建唯一性。我在这里分享您的数据的静态和动态透视。在动态枢轴中，如果您有 3 名或 10 名玩家，它会以您需要的格式提供您的数据。但是如果你的球队名单和球员名单都是固定的，那么你可以选择静态支点，因为它会更快。

在动态数据透视表中，我已将您的数据创建为表 t。您可以将整个选择查询替换为t。

架构：

 create table t (team   int, name   varchar(50) ,rank int);
 insert into t values(1,    '1Player1', 1);
 insert into t values(1,    '1Player2', 2);
 insert into t values(1,    '1Player3', 2);
 insert into t values(1,    '1Player4', 2);
 insert into t values(1,    '1Player5', 3);
 insert into t values(1,    '1Player6', 4);
 insert into t values(1,    '1Player7', 5);
 insert into t values(2,    '2Player1', 1);
 insert into t values(2,    '2Player2', 2);
 insert into t values(2,    '2Player3', 2);
 insert into t values(2,    '2Player4', 2);

查询#1（静态枢轴）

   SELECT team, MAX(IF(concat(rank,right(name,3)) = '1er1', concat(rank,name), NULL)) AS "1",
    MAX(IF(concat(rank,right(name,3)) = '2er2', concat(rank,name), NULL)) AS "2",
    MAX(IF(concat(rank,right(name,3)) = '2er3', concat(rank,name), NULL)) AS "2",
    MAX(IF(concat(rank,right(name,3)) = '2er4', concat(rank,name), NULL)) AS "2",
    MAX(IF(concat(rank,right(name,3)) = '3er5', concat(rank,name), NULL)) AS "3",
    MAX(IF(concat(rank,right(name,3)) = '4er6', concat(rank,name), NULL)) AS "4",
    MAX(IF(concat(rank,right(name,3)) = '5er7', concat(rank,name), NULL)) AS "5" 
    FROM (SELECT tm.team_id AS team, pp.user_name AS name, tm.rank AS rank
FROM teams_members AS tm 
    LEFT JOIN players_profiles AS pp
    ON pp.uid=tm.user_id
WHERE tm.team_id = 1 OR tm.team_id = 2
ORDER BY  tm.team_id, tm.rank)t
    GROUP BY team

查询#2（动态枢轴）

 SET @sql = NULL;
 SELECT
   GROUP_CONCAT(DISTINCT
     CONCAT(
       'MAX(IF(concat(rank,right(name,3)) = ''',
       concat(rank,right(name,3)),
       ''', concat(rank,name), NULL)) AS ',
       concat('"',rank,'"')
     )
   ) INTO @sql
 FROM t;
 
 SET @sql = CONCAT('SELECT team
                     , ', @sql, ' 
                    FROM t
                    GROUP BY team');
 
 PREPARE stmt FROM @sql;
 EXECUTE stmt;
 DEALLOCATE PREPARE stmt;

输出：

team	1	2	2	2	3	4	5
1	11Player1	21Player2	21Player3	21Player4	31Player5	41Player6	51Player7
2	12Player1	22Player2	22Player3	22Player4	null	null	null

db小提琴here