Mysql:在 select 语句中创建内联表？

Question

有没有办法在 MySql 中创建一个用于连接的内联表？

类似:

SELECT LONG [1,2,3] as ID, VARCHAR(1) ['a','b','c'] as CONTENT

那会输出

|  ID  |  CONTENT  |
| LONG | VARCHAR(1)|
+------+-----------+
|   1  |    'a'    |
|   2  |    'b'    |
|   3  |    'c'    |

我可以像这样在连接中使用:

SELECT 
  MyTable.*,
  MyInlineTable.CONTENT
FROM
  MyTable
  JOIN 
    (SELECT LONG [1,2,3] as ID, VARCHAR(1) ['a','b','c'] as CONTENT MyInlineTable)
  ON MyTable.ID = MyInlineTable.ID

我意识到我可以做到

SELECT 1,'a' UNION SELECT 2,'b' UNION SELECT 3,'c'

但这看起来很邪恶

我不想执行存储过程，因为 a、b、c 可能会在每次查询和数据大小时发生变化。还需要将存储过程保存在数据库中，我不想为此修改数据库。 View 是一样的。

我真正想要的是用更好的语法来执行 SELECT 1,'a' UNION SELECT 2,'b' UNION SELECT 3,'c' 的东西。

Answer 1

我现在能记住的唯一方法是使用 UNION 或创建一个 TEMPORARY TABLE 并将这些值插入其中。适合你吗？

---

TEMPORARY_TABLE(经过测试并且有效):

创作:

CREATE TEMPORARY TABLE MyInlineTable (id LONG, content VARCHAR(1) );

INSERT INTO MyInlineTable VALUES
(1, 'a'),
(2, 'b'),
(3, 'c');

用法:

SELECT 
  MyTable.*,
  MyInlineTable.CONTENT
FROM
  MyTable
  JOIN 
    SELECT * FROM MyInlineTable;
  ON MyTable.ID = MyInlineTable.ID

---

TEMPORARY_TABLES 生命周期 (reference) :

Temporary tables are automatically dropped when they go out of scope, unless they have already been explicitly dropped using DROP TABLE:

.

All other local temporary tables are dropped automatically at the end of the current session.

.

Global temporary tables are automatically dropped when the session that created the table ends and all other tasks have stopped referencing them. The association between a task and a table is maintained only for the life of a single Transact-SQL statement. This means that a global temporary table is dropped at the completion of the last Transact-SQL statement that was actively referencing the table when the creating session ended.`