MySQL 8 递归 CTE 为每个项目创建行

Question

我想从一个不存在的 table:

创建一个数据 return

+-------+--------+------------+
| type  | name   | expiration |
+-------+--------+------------+
| fruit | orange | 1999-12-31 |
| fruit | banana | 1999-12-31 |
| fruit | apple  | 1999-12-31 |
| fruit | orange | 2000-01-01 |
| fruit | banana | 2000-01-01 |
| fruit | apple  | 2000-01-01 |
+-------+--------+------------+

每个水果都有一行具有相同的日期。然后日期增加一天，并为该日期为每个水果创建一行。

到目前为止我有这个查询：

WITH RECURSIVE cte  
AS (
      SELECT 
          "fruit" as `type`
          ,"orange" as `name`
          ,"1999-12-31" as `expiration`
      UNION ALL
      SELECT 
          "fruit" as `type`
          ,"banana" as `name`
          ,date_add(`expiration`, INTERVAL 1 DAY) as `expiration`
      FROM cte 
      WHERE `expiration` < "2000-01-01"
    )
SELECT *
FROM cte
;

生成：

+-------+--------+------------+
| type  | name   | expiration |
+-------+--------+------------+
| fruit | orange | 1999-12-31 |
| fruit | banana | 2000-01-01 |
+-------+--------+------------+

我认为可以通过在具有水果名称的临时 fruit_list table 中执行递归 CTE select 内部来解决该问题，但我不知道如何实现那个。

例子fruit_listtable:

CREATE TEMPORARY TABLE IF NOT EXISTS `fruit_list` (
    `name` varchar(128) NOT NULL
) ENGINE = InnoDB;

INSERT INTO `fruit_list` VALUES
("orange")
,("banana")
,("apple")
;

我想用常规查询而不是过程来解决问题。可能吗？

解决方案的目的是有一个查询，可以 return 每个水果和日期范围的一些测试数据。

Answer 1

您可以通过一系列交叉连接来处理此问题：

SELECT
    f.type,
    n.name,
    e.expiration
FROM (SELECT 'fruit' AS type) f
CROSS JOIN
(
    SELECT 'orange' AS name UNION ALL
    SELECT 'banana' UNION ALL
    SELECT 'apple'
) n
CROSS JOIN
(
    SELECT '1999-12-31' AS expiration UNION ALL
    SELECT '2000-01-01'
) e
ORDER BY
    f.type,
    e.expiration,
    n.name;

Demo

Answer 2

对于那些想使用临时 table 的人，这里是代码：

CREATE TEMPORARY TABLE IF NOT EXISTS `fruit_list` (
    `name` varchar(128) NOT NULL
) ENGINE = InnoDB;

INSERT INTO `fruit_list` VALUES
("orange")
,("banana")
,("apple")
;

WITH RECURSIVE cte  
AS (
      SELECT 
        "1999-12-30" as `expiration`
      UNION ALL
      SELECT 
          date_add(`expiration`, INTERVAL 1 DAY) as `expiration`
      FROM cte 
      WHERE `expiration` < "2000-01-02"
    )
,cte1 as (
    SELECT * FROM cte
    CROSS JOIN `fruit_list`
)
SELECT     
    "fruit" as `type`
    ,`name`
    ,`expiration`
FROM cte1
ORDER BY
    `expiration`
    ,`name`
;

结果：

+-------+--------+------------+
| type  | name   | expiration |
+-------+--------+------------+
| fruit | apple  | 1999-12-30 |
| fruit | banana | 1999-12-30 |
| fruit | orange | 1999-12-30 |
| fruit | apple  | 1999-12-31 |
| fruit | banana | 1999-12-31 |
| fruit | orange | 1999-12-31 |
| fruit | apple  | 2000-01-01 |
| fruit | banana | 2000-01-01 |
| fruit | orange | 2000-01-01 |
| fruit | apple  | 2000-01-02 |
| fruit | banana | 2000-01-02 |
| fruit | orange | 2000-01-02 |
+-------+--------+------------+
12 rows in set (0.00 sec)

MySQL 8 递归 CTE 为每个项目创建行

MySQL 8 Recursive CTE Create row for each item

foreach

recursive-query

common-table-expression

mysql-8.0

Demo