SeedTable.SomeColumn 递归 CTE 中的 +1 未按预期工作

Question

我正在 Redshift 中尝试这个查询：

WITH  RECURSIVE CTE AS
        (
        SELECT  id
        ,       managerid
        ,       name
        ,       1 AS level
        FROM    users parent
        WHERE   name = 'Jason Ramsay'
        UNION ALL
        SELECT  child.id
        ,       child.managerid
        ,       child.name
        ,       level +1
        FROM    users child, users parent
        WHERE   child.managerid = parent.id
        )
SELECT *
FROM    CTE

但我不断收到此错误：(500310) 无效操作：列“级别”在子项、父项中不存在； 1 个语句失败。

我做错了什么？根据我在这里找到的文档，Redshift 接受递归，这是解决它的方法： https://docs.aws.amazon.com/redshift/latest/dg/r_WITH_clause.html#r_WITH_clause-recursive-cte

Answer 1

我相信对于递归cte，cte本身必须在union all部分被引用：

WITH RECURSIVE cte AS (
    SELECT id
         , managerid
         , name
         , 1 AS level
    FROM users parent
    WHERE name = 'Jason Ramsay'

    UNION ALL

    SELECT child.id
         , child.managerid
         , child.name
         , level + 1
    FROM cte parent -- <<-- this
    JOIN users child ON parent.id = child.managerid
)
SELECT *
FROM cte

您链接到的文档清楚地提到了这一点：

recursive_query A UNION ALL query that consists of two SELECT subqueries:

The first SELECT subquery doesn't have a recursive reference to the same CTE_table_name. [...]

The second SELECT subquery references the same CTE_table_name in its FROM clause. [...]

SeedTable.SomeColumn 递归 CTE 中的 +1 未按预期工作

SeedTable.SomeColumn +1 in a recursive CTE not working as expected

sql

recursive-query

amazon-redshift