使用Postgresql解决以下问题的最佳方法是什么?
对于每一行,我根据另一个表中的SELECT插入到文章表中,我想更新插入文章的某些列。
这是我目前的解决方案:
-- temporarily alter table to avoid not null issues
ALTER TABLE article ALTER COLUMN fk_article_unit DROP NOT NULL;
(...)
--create article and return inserted pks, store these in a temporary table so they can be used for all following updates
WITH articles AS (
insert into article
(
...
)
select
...
from other_table
where some_condition
RETURNING pk
)
SELECT pk INTO temporary temp_articles
FROM articles;
-- update various fk for all newly created articles
UPDATE article
SET fk_article_type =
(SELECT pk
FROM article_type
WHERE unique_id = 'service')
WHERE pk in (select pk from temp_articles);
UPDATE article
SET fk_article_type =
(SELECT min(pk)
FROM vat_code)
WHERE fk_article_type is null;
(... several more updates)
--readd no null constraint
ALTER TABLE article ALTER COLUMN fk_article_type SET NOT NULL;
(...)
答案 0 :(得分:1)
我不明白为什么使用单个insert
查询无法做到这一点。如果以下解决方案不适用,请提供有关您的数据模型的一些其他信息。
insert into article
(
...,
fk_article_type
)
select
...,
coalesce -- if first query is null, then the result of second will be used
(
( -- 1st query
select pk from article_type where unique_id= 'service'
),
( -- 2nd query
select min(pk) from vat_code
)
)
from other_table
where some_condition
returning pk;