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PostgreSQL with-delete“关系不存在”

2020-07-16 Postgre SQL 前端之家

前端之家收集整理的这篇文章主要介绍了PostgreSQL with-delete“关系不存在”，前端之家小编觉得挺不错的，现在分享给大家，也给大家做个参考。

@H_403_0@ 我正在使用postgresql 9.1,我想使用这个提示从我的表中删除重复项：
https://stackoverflow.com/a/3822833/2239537

所以,我的查询看起来像这样：

WITH cte
 AS (SELECT ROW_NUMBER() 
 OVER (PARTITION BY code,card_id,parent_id 
     ORDER BY id DESC) RN
     FROM card)
DELETE FROM cte
WHERE RN > 1

但它告诉我

ERROR: relation "cte" does not exist
sql state: 42P01
Character: 157

但是这个说法很好：

WITH cte
 AS (SELECT ROW_NUMBER() 
 OVER (PARTITION BY code,parent_id 
     ORDER BY id DESC) RN
     FROM merchantcard)
SELECT * FROM cte
WHERE RN > 1

任何想法如何让它工作？
谢谢！

这是因为Postgresql中的CTE与sql Server中的CTE不同.在sql Server中,CTE就像一个可更新的视图,所以你可以从它们中删除或更新它们,在Postgresql中你不能.

你可以加入cte和delete,如：

with cte as (
    select
        id,row_number() over(partition by code,parent_id order by id desc) as rn
    from card
)
delete
from card
where id in (select id from cte where rn > 1)

另一方面,您可以在Postgresql中的CTE中编写DDL语句(参见documentation),这可能非常方便.例如,您可以从卡中删除所有行,然后仅插入具有row_number = 1的行：

with cte1 as (
    delete
    from card
    returning *
),cte2 as (
    select
        row_number() over(partition by code,parent_id order by id desc) as rn,*
    from cte1
)
insert into card
select <columns here>
from cte2
where rn = 1

原文链接：https://www.f2er.com/postgresql/192040.html