如何从 PostgreSQL 中的递归查询设置值？

Question

我有一个给出结果的查询：

id | manager_id | level | star_level 
----+------------+-------+------------
  1 |       NULL |     1 |          0
  2 |          1 |     2 |          1
  3 |          2 |     3 |          1
  4 |          3 |     4 |          2
  5 |          4 |     5 |          2
  6 |          5 |     6 |          2
  7 |          6 |     7 |          3
  8 |          7 |     8 |          3
  9 |          8 |     9 |          4
(9 rows)

这里是查询：

WITH RECURSIVE parents AS (
  SELECT e.id
       , e.manager_id
       , 1 AS level
       , CAST(s.is_star AS INTEGER) AS star_level
    FROM employees AS e
         INNER JOIN skills AS s
            ON e.skill_id = s.id
   WHERE manager_id IS NULL
UNION ALL
  SELECT e.id
       , e.manager_id
       , p.level + 1 AS level
       , p.star_level + CAST(s.is_star AS INTEGER) AS star_level
    FROM employees AS e
         INNER JOIN skills AS s
            ON e.skill_id = s.id
         INNER JOIN parents AS p
            ON e.manager_id = p.id
   WHERE e.manager_id = p.id
)
SELECT *
  FROM parents
;

能否告诉我如何更改查询，以便在同一查询中将级别和 star_level 值写入相应的列？

演示数据：

create table Employees(
    id INT,
    name VARCHAR,
    manager_id INT,
    skill_id INT,
    level INT,
    star_level INT
    
);

 create table Skills(
    id INT,
    name VARCHAR,
    is_star BOOL
);

INSERT INTO Employees
    (id, name, manager_id, skill_id)
VALUES
    (1, 'Employee 1', NULL, 1),
    (2, 'Employee 2', 1, 2),
    (3, 'Employee 3', 2, 3),
    (4, 'Employee 4', 3, 4),
    (5, 'Employee 5', 4, 5),
    (6, 'Employee 6', 5, 1),
    (7, 'Employee 7', 6, 2),
    (8, 'Employee 8', 7, 3),
    (9, 'Employee 9', 8, 4)
    ;

INSERT INTO Skills
    (id, name, is_star)
VALUES
    (1, 'Skill 1', FALSE),
    (2, 'Skill 2', TRUE),
    (3, 'Skill 3', FALSE),
    (4, 'Skill 4', TRUE),
    (5, 'Skill 5', FALSE)
    ;

因此，我需要一个查询，该查询将计算 Employees table 的级别和 star_level 列，并在一个查询中写入它们的值（在 Employees table 中）。

Answer 1

您可以将 UPDATE 语句与您的 CTE 一起使用：

with recursive parents as (
 ... your original query goes here ...
)
update employees
  set level = p.level, 
      star_level = p.star_level
from parents p
where employees.id = p.id;

如何从 PostgreSQL 中的递归查询设置值？

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