Mysql 将列作为行返回

我有一张有一些名字参考的桌子

对于查询：

SELECT id, n1, n2, n3
FROM nametable

该表返回：

+----+--------+-------+--------+ | id | n1 | n2 | n3 | +----+--------+-------+--------+ | 1 | Larry | Bob | Mo | | 2 | Sara | May | (NULL) | | 3 | Keiran | Lenny | (NULL) | +----+--------+-------+--------+ +----+--------+-------+--------+ |id | n1 | n2 | n3| +----+--------+-------+--------+ |1 |拉里|鲍勃|莫| |2 | Sara | May |（空）| |3 | Keiran | Lenny |（空）| +----+--------+-------+--------+ 我想把它作为：

+----+--------+ | id | n | +----+--------+ | 1 | Larry | | 1 | Bob | | 1 | Mo | | 2 | Sara | | 2 | May | | 3 | Keiran | | 3 | Lenny | +----+--------+ +----+--------+ |id | n| +----+--------+ |1 |拉里| |1 |鲍勃| |1个月| |2 |萨拉| |5月2日| |3 |凯兰| |3 |伦尼| +----+--------+ 请注意，（NULL）值不会在最终结果中返回

我做了一些研究，发现了一种叫做“透视表”的东西。然而，没有一个例子符合我的条件。我想在每一行保留id

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如何使用查询实现这一点？

我认为这是mysql中最接近的：

select * from (
(select id, n1 as n from nametable) union all
(select id, n2 as n from nametable) union all
(select id, n3 as n from nametable)
) x

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您也可以通过这种方式取消桌面打印

SELECT id, 
       CASE n 
          WHEN 1 THEN n1
          WHEN 2 THEN n2
          WHEN 3 THEN n3
       END n
  FROM nametable t CROSS JOIN
(
  SELECT 1 n UNION ALL
  SELECT 2 UNION ALL
  SELECT 3 
) i
HAVING n IS NOT NULL
 ORDER BY id, n;

输出：

| ID | N | |----|--------| | 1 | Bob | | 1 | Larry | | 1 | Mo | | 2 | May | | 2 | Sara | | 3 | Keiran | | 3 | Lenny | |ID | N| |----|--------| |1 |鲍勃| |1 |拉里| |1个月| |5月2日| |2 |萨拉| |3 |凯兰| |3 |伦尼|

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这里有一个演示

我不相信MySQL有像SQL Server这样的

枢轴。