MySql 递归 - 从给定的 id 获取所有 children 和 parents

Question

MySQL 版本 8.0 架构 SQL

CREATE TABLE IF NOT EXISTS `department` (
  `id` INT NOT NULL,
  `name` VARCHAR(45) NOT NULL,
  `father` INT NULL,
  PRIMARY KEY (`id`),
  INDEX `fk_department_department_idx` (`father` ASC) VISIBLE,
  CONSTRAINT `fk_department_department`
    FOREIGN KEY (`father`)
    REFERENCES `department` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

insert into department (id,name,father)
values
(1, 'dp1',null),
(2, 'dp2',null),
(3, 'dp3',1),
(4, 'dp4',1),
(5, 'dp5',2),
(6, 'dp6',4),
(7, 'dp7',6),
(8, 'dp8',6),
(9, 'dp9',6);

SET GLOBAL sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));
SET SESSION sql_mode = '';

我的查询：

WITH RECURSIVE cte_department AS (
      SELECT 
          d1.id, 
          d1.name, 
          d1.father
      FROM
          department d1
      WHERE
          d1.id=6
    UNION ALL
      SELECT 
          d2.id, 
          d2.name, 
          d2.father
      FROM
          department d2
      INNER JOIN cte_department cte ON cte.id = d2.father
)
SELECT * FROM cte_department;

结果：

id  name    father
6   dp6      4
7   dp7      6
8   dp8      6
9   dp9      6

我需要的：

id  name    father
1   dp1      null
4   dp4      1
6   dp6      4
7   dp7      6
8   dp8      6
9   dp9      6

问题是：我可以获得所有子项，但我需要将给定 ID 中的所有 parents 添加到此查询中，在本例中为 ID 6。我坚持这一点。如果有人可以帮助我，请关注 fiddle.

https://www.db-fiddle.com/f/g8YkE3hqsvaw8G9vdHPyyF/0

Answer 1

递归部分可以有多个查询块。

WITH RECURSIVE cte_department AS (
      SELECT 
          d1.id,
          d1.name,
          d1.father,
          'Begin' state
      FROM
          department d1
      WHERE
          d1.id=6
    UNION ALL
      SELECT 
          d2.id,
          d2.name,
          d2.father,
          'Up'
      FROM
          department d2
      INNER JOIN
          cte_department cte
      ON
          cte.father = d2.id
      WHERE
          cte.state in ('Begin', 'Up')
    UNION ALL
      SELECT 
          d2.id,
          d2.name,
          d2.father,
          'Down'
      FROM
          department d2
      INNER JOIN
          cte_department cte
      ON
          cte.id = d2.father
      WHERE
          cte.state in ('Begin', 'Down')
)
SELECT
    id, name, father
FROM
    cte_department
ORDER BY
    father, id, name;

在 db<>fiddle 上试用。

Answer 2

我会使用两个单独的递归查询：一个用于获取 children，另一个用于 parents，然后是 union 结果。您可以跟踪每个节点的级别，以便在结果集中对记录进行正确排序：

with recursive 
    children as (
        select 1 as lvl, d.* from department d where id = 6
        union all
        select c.lvl, d.* from department d inner join children c on c.id = d.father
    ),
    parents as (
        select 1 as lvl, d.* from department d where id = 6
        union all
        select p.lvl - 1, d.* from department d inner join parents p on d.id = p.father
    )
select * from parents
union   -- on purpose, to remove the duplicate on id 6
select * from children
order by lvl;

这比在同一个查询中有多个 union all 成员更安全。 MySQL 不保证递归中成员的求值顺序，因此使用此技术可能会导致意外行为。

Demo on DB Fiddle

与你的问题无关，但是：在你的代码中可以看到以下内容：

SET GLOBAL sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));
SET SESSION sql_mode = '';

只是不要。 ONLY_FULL_GROUP_BY 有一个很好的理由，那就是让 MySQL 在聚合查询方面与 SQL 标准一致。禁用此 SQL 模式绝不是一个好主意。

MySql 递归 - 从给定的 id 获取所有 children 和 parents

MySql Recursive - get all children and parents from a given id

mysql

sql

common-table-expression

hierarchical-data

recursive-query